Podio users can mention other users in comments using mentioning, but I can't find any instance of it in the Podio API documentation. Is this not technically feasible to do via API?
I've tried just manually having "@" "@<user_id>" "@" and these appear as plaintext and don't send an alert to the user
Yes, you will want to have the "value" of the comment contain the markdown for @metnion links. Which in this case is:
@[Person's Name](user:userId)