https://supabase.com/pricing - 500MB, 2GB download/month (can be used as plain PostgreSQL)
https://www.cockroachlabs.com/pricing - 5GB, 250M "request units"/month (distributed, PostgreSQL-ish https://www.cockroachlabs.com/docs/stable/postgresql-compati...)
I was not aware of the other portions of the free compute tier from Fly.io, was looking into Oracle Cloud. (Ask HN: What cool stuff do you run free-tier? Sep 2021 https://news.ycombinator.com/item?id=28652736)