It would host webapps like yours that use in browser sqlite to store data, then the service provide a sync their sqlite data across different devices. The user not the app would pay for the storage of the data, so they would own their data. And you can use CSP to lock down the app from sharing with other domains, meaning an app can't leak your data.
The service would handle identity (only you can access your sqlite data - the app just ) and could provide an app store like experience with different apps of this type.
Sort of like a firebase style backend as a service, but the user would own the data instead of the app.
The concept I'm thinking about is different - it doesn't run any app code on the server, the apps are SPAs that run in the browser only (no backend supporting code), and then the server just syncs the data from the apps. This means the apps can focus on building ux/business logic and not worry about database, how data gets to/from clients, identity, etc. Somewhat like firebase but where the users pays for the server, not the app. That should hopefully be simpler for developers, and theres a lot less likelihood of issues with server config/etc (although presumably pikapod will handle that). It should also be cheaper since you're not constantly running a container, just storing data.
I'm not sure if it's a useful concept or not yet :)
Someone here needs exactly that: https://news.ycombinator.com/item?id=42502576 (And possibly me too.) So yeah, please do continue and then publish it.
It's self-hosted and all packed into SQLite so, IMO, very portable.
Recently added a trick to snapshot all the public links I save - my copy and on Archive.is - link rot is real.