Presuming by “Ruby” you meant Rails, you probably won’t find WordPress a satisfactory replacement for any of them if you’re more of a developer than a site-builder. As a web development framework, WordPress is nearly useless computers to the others.

Django has run fine on SQLite for well over a decade at this point.

Really?

Yea to be honest, I program in .net for a living, but I've been looking for a simple SAAS on the side.

I've been looking for a simple plugin type solution. Django, RoR, etc all have the promise of third party packages but honestly most wordpress templates are easy and more feature rich for alot of things.

SQLite along with a jam stack service for auth would make my life super easy.