Just discovered https://www.getgrist.com/. I have been on the hunt for an open-source alternative to Airtable that can also be self-hosted. So far I have tried out baserow.io, but it greatly lacks in features (veryy limited field types) and programmability.
Checked out some templates on the Grist website and it looks a lot more promising! Going to try it out on their website (it's completely free for personal use) since they provide a migration path for your data on to a personal instance.