How far can you go in customizing Kobo e-reader?

Hello everyone,

I'm new in this forum. In advance, thanks a lot for your help that will help me a lot on my project.

I want to use a Kobo e-reader for a personal project: I want to convert the reader into a very "dumb" smartphone (calendar, weather, notes, time, books of course...)

1st question: based on your experience, do you think it's do-able ? If yes, what e-reader would you recommend ?

2nd question: what language do you recommend ? I'm already knowledgeable in Python and it would be great if I could use it.

3rd question: what would be the best way to start with, apart from digging into this forum ? Any tutorial you are aware of ? Similar project on github?
So far, I hardly found anything.

Thanks a lot for your help!
Pierre (I'm French:) )