As a sideproject I have an idea to build an app, that'll eventually have frontends on multiple platforms, smart tvs, phones, tablets and web.

I have never built an app from scratch before, so the I am afraid of the journey, I also want to plan things properly so I can sleep well at night, not thinking about crashes that might happen.

How do I decide which stack to use? Should I start with the DB schema? Do I even need to use SQL? Should I go with NoSQL? Firebase or Supabase? Why? GraphQL or REST? Why?

I am aware that these are decisions are hard to make without knowing anything about the project or the actual data, but I just want to get a general idea of how the process is laid out!

Thanks.