If you want to do the same as you do with Postgres or Mongo, and solve the different Fly accounts issue, you can use Query (I’m the author).
Query is a Rust server for your remote SQLite databases and a CLI to manage them.
To set up a staging environment, you can create a branch from a production database and work with it. Essentially, a branch is a copy of the database that allows you to use the same data as in the production database and make modifications to it without affecting your production environment. This ensures that any changes you make can be safely tested and refined before being implemented in the live environment.