There has been at least 3 efforts to expand the dumptxoutset command to be able to export the data as CSV:

• rpc: allow dumptxoutset to dump human-readable data #18689
• rpc: allow dumptxoutset to dump human-readable data #24202
• luke-jr/bitcoin#rpc_dumptxoutset_hr

JSON export also has been requested: #21670

Lately @theStack suggested that we can leverage the SQLite format for the export.

I think this is the best approach since it is trivial to export both CSV and JSON from SQLite + you can access the file programatically via virtually any programming language:

• sqlite3 -header -csv foo.db "select * from foo" > foo.csv
• sqlite3 -json foo.db "select * from foo" > foo.json

... and we already have SQLite as an optional dependency. Such format is also future proof (we can add new table columns if needed).