I have just successfully deployed the Elastic Stack to a Raspberry Pi 4 Ubuntu20.04 environment.
Obviously Elasticsearch is supported so that was a breeze, the tricky part was Kibana as it doesn't have an official Arm release.
TLDR the version of node.js Kibana ships with needs replacing with the arm64 version.
I am just carrying out some testing but once done I will release a guide (On this topic) with the steps I took so anyone interested in using a similar setup can follow along.
This will make a great home SIEM as well as provide overall network visibility.