"Sqlite [...] encryption extension is a $2000 add-on".

SqliteMultipleCiphers has been around for ages and is free https://utelle.github.io/SQLite3MultipleCiphers/

And Turso Database supports encryption out of the box: https://docs.turso.tech/tursodb/encryption

There’s also SQLCipher, it’s been in development since 2009 and works quite well:

https://github.com/sqlcipher/sqlcipher