Include specific fields from document using Ingest pipeline

Elastic Stack Elasticsearch
1

Hi
I am ingesting following document to elasticsearch directly . First I am only interested in wprss_ftp_feed_source and its values and exclude all other fields before they are ingested into index .

second after selecting the wprss_ftp_feed_source , I am also looking to ingesting the values as individual fields in a document .

I am looking for guide line ,which pipeline processor of ingest pipeline I can use to achive above

"meta": {
 "wprss_ftp_taxonomies": [
   {
     "value": "a:0:{}",
     "raw": "a:0:{}",
     "boolean": false,
     "date": "1971-01-01",
     "datetime": "1971-01-01 00:00:01",
     "time": "00:00:01"
   }
 ],
 "wprss_ftp_feed_source": [
   {
     "value": "14",
     "raw": "14",
     "long": 14,
     "double": 14,
     "boolean": false,
     "date": "1971-01-01",
     "datetime": "1971-01-01 00:00:01",
     "time": "00:00:01"
   }
 ],
 "wprss_ftp_media:thumbnail": [
   {
     "value": "",
     "raw": "",
     "boolean": false,
     "date": "1971-01-01",
     "datetime": "1971-01-01 00:00:01",
     "time": "00:00:01"
   }
 ],
2

I would try JSON processor | Elasticsearch Reference [7.10] | Elastic and set field to meta. wprss_ftp_feed_source and see if that works (I didn't try it though sorry, just an idea to start).