Anything else missing to get .NET metrics to Kibana other than (Elasticsearch, APM-Server, Kibana)?

The documentation is confusing, it's a lot and I'm lost.
Simply I want metrics from .NET to appear in Kibana.
Here's my full installation:

this is the docker-compose.yml file:

version: "2.2"

services:
  setup:
    image: docker.elastic.co/elasticsearch/elasticsearch:${STACK_VERSION}
    volumes:
      - certs:/usr/share/elasticsearch/config/certs
    user: "0"
    command: >
      bash -c '
        if [ x${ELASTIC_PASSWORD} == x ]; then
          echo "Set the ELASTIC_PASSWORD environment variable in the .env file";
          exit 1;
        elif [ x${KIBANA_PASSWORD} == x ]; then
          echo "Set the KIBANA_PASSWORD environment variable in the .env file";
          exit 1;
        fi;
        if [ ! -f config/certs/ca.zip ]; then
          echo "Creating CA";
          bin/elasticsearch-certutil ca --silent --pem -out config/certs/ca.zip;
          unzip config/certs/ca.zip -d config/certs;
        fi;
        if [ ! -f config/certs/certs.zip ]; then
          echo "Creating certs";
          echo -ne \
          "instances:\n"\
          "  - name: es01\n"\
          "    dns:\n"\
          "      - es01\n"\
          "      - localhost\n"\
          "    ip:\n"\
          "      - 127.0.0.1\n"\
          > config/certs/instances.yml;
          bin/elasticsearch-certutil cert --silent --pem -out config/certs/certs.zip --in config/certs/instances.yml --ca-cert config/certs/ca/ca.crt --ca-key config/certs/ca/ca.key;
          unzip config/certs/certs.zip -d config/certs;
        fi;
        echo "Setting file permissions"
        chown -R root:root config/certs;
        find . -type d -exec chmod 750 \{\} \;;
        find . -type f -exec chmod 640 \{\} \;;
        echo "Waiting for Elasticsearch availability";
        until curl -s --cacert config/certs/ca/ca.crt https://es01:9200 | grep -q "missing authentication credentials"; do sleep 30; done;
        echo "Setting kibana_system password";
        until curl -s -X POST --cacert config/certs/ca/ca.crt -u "elastic:${ELASTIC_PASSWORD}" -H "Content-Type: application/json" https://es01:9200/_security/user/kibana_system/_password -d "{\"password\":\"${KIBANA_PASSWORD}\"}" | grep -q "^{}"; do sleep 10; done;
        echo "All done!";
      '
    healthcheck:
      test: ["CMD-SHELL", "[ -f config/certs/es01/es01.crt ]"]
      interval: 1s
      timeout: 5s
      retries: 120

  es01:
    depends_on:
      setup:
        condition: service_healthy
    image: docker.elastic.co/elasticsearch/elasticsearch:${STACK_VERSION}
    volumes:
      - certs:/usr/share/elasticsearch/config/certs
      - esdata01:/usr/share/elasticsearch/data
    ports:
      - ${ES_PORT}:9200
    environment:
      - node.name=es01
      - cluster.name=${CLUSTER_NAME}
      - discovery.type=single-node
      - ELASTIC_PASSWORD=${ELASTIC_PASSWORD}
      - bootstrap.memory_lock=true
      - xpack.security.enabled=true
      - xpack.security.http.ssl.enabled=true
      - xpack.security.http.ssl.key=certs/es01/es01.key
      - xpack.security.http.ssl.certificate=certs/es01/es01.crt
      - xpack.security.http.ssl.certificate_authorities=certs/ca/ca.crt
      - xpack.security.transport.ssl.enabled=true
      - xpack.security.transport.ssl.key=certs/es01/es01.key
      - xpack.security.transport.ssl.certificate=certs/es01/es01.crt
      - xpack.security.transport.ssl.certificate_authorities=certs/ca/ca.crt
      - xpack.security.transport.ssl.verification_mode=certificate
      - xpack.license.self_generated.type=${LICENSE}
    mem_limit: ${MEM_LIMIT}
    ulimits:
      memlock:
        soft: -1
        hard: -1
    healthcheck:
      test:
        [
          "CMD-SHELL",
          "curl -s --cacert config/certs/ca/ca.crt https://localhost:9200 | grep -q 'missing authentication credentials'",
        ]
      interval: 10s
      timeout: 10s
      retries: 120

  kibana:
    depends_on:
      es01:
        condition: service_healthy
    image: docker.elastic.co/kibana/kibana:${STACK_VERSION}
    volumes:
      - certs:/usr/share/kibana/config/certs
      - kibanadata:/usr/share/kibana/data
    ports:
      - ${KIBANA_PORT}:5601
    environment:
      - SERVERNAME=kibana
      - ELASTICSEARCH_HOSTS=https://es01:9200
      - ELASTICSEARCH_USERNAME=kibana_system
      - ELASTICSEARCH_PASSWORD=${KIBANA_PASSWORD}
      - ELASTICSEARCH_SSL_CERTIFICATEAUTHORITIES=config/certs/ca/ca.crt
      - xpack.fleet.packages=[apm]
    mem_limit: ${MEM_LIMIT}
    healthcheck:
      test:
        [
          "CMD-SHELL",
          "curl -s -I http://localhost:5601 | grep -q 'HTTP/1.1 302 Found'",
        ]
      interval: 10s
      timeout: 10s
      retries: 120

  apm-server:
    image: docker.elastic.co/apm/apm-server:${STACK_VERSION}
    depends_on: ['es01', 'kibana']
    healthcheck:
      test: curl --cacert /usr/share/elasticsearch/config/certs/ca/ca.crt -s https://localhost:8200/healthcheck >/dev/null; if [[ $$? == 52 ]]; then echo 0; else echo 1; fi
      interval: 30s
      timeout: 10s
      retries: 5
    environment:
      - output.elasticsearch.hosts=["es01:9200"]
      - output.elasticsearch.username=elastic
      - output.elasticsearch.password="123456"
    ports:
      - 8200:8200

volumes:
  certs:
    driver: local
  esdata01:
    driver: local
  kibanadata:
    driver: local

I hope I don't need to use Fleet, as I read somewhere that it is not required with single node cluster (it is becoming a plethora of services already), I managed to make way more progress with Prometheus and Grafana.

My .NET application:

  "ElasticApm": {
    "ServiceName": "my-service-name",
    "SecretToken": "",
    "ServerUrl": "http://localhost:8200",
    "Environment": "my-environment"
  }

I have a very simple metric (System.Diagnostics.Metrics.Counter) that gets incremented randomly using a hosted background service (for testing):

        public void AddMessage(Dictionary<string, object> attributes)
        {
            _messageCounter.Add(1, attributes.Select(x => x).ToArray());
        }

I hope I see this metric in Kibana somehow.
and of course I added the middleware:

var app = builder.Build(); 
app.UseAllElasticApm(builder.Configuration);

Anything missing, is there a specific configuration needed to be sorted in Kibana to find the Agent? I know of some settings but they are in the Fleet section, which as I mentioned not required...

When I go to http://localhost:5601/app/apm/services
I see a blank page with a link to "Add data", when I go to it's page: it lists two types of services:
APM Server: which I have already installed as part of my docker-compose file. and 'Check APM Server status' prompts with: "You have correctly setup APM Server"

the other service is APM Agent, when I 'Check agent status', again, it gives a nice green message "Data successfully received from one or more agents" - Does this mean it can see my .NET application??

Thanks for your help