Ask HN: Reliability of Raspberry Pi for production Django app

Pis can be made relatively reliable, but it's extra effort (read-only or no SD card, making sure power supply is good, ...). For a business scenario, I'd consider a mini-PC instead: they're not that much more expensive than a Pi once you're done with all the parts, more reliable out of the box and easy to replace if needed in the future.

Performance-wise it should be fine given the expected workload. I'd suggest just using SQLite in this case instead of a dedicated DB server.

Your biggest concern here would be storage and backups. Considering the little amount of data as well as low volume of changes, I think a daily backup will be more than enough and can be done by just encrypting then emailing the SQLite DB file.