Vortex Sound Research

Don't hope this is a bit too much off-topic but...

I really want to learn how to play the keys (piano, synthesizer, keyboard). I mostly create synthesizer beep-boop music, but I really want to get better at live playing, creating melodies, chords, chord progressions, go from loop to song, etc.

So I looked up piano lessons but those are... well... expensive.

Then I looked at apps (because they are cheaper), but - besides from the first 1000 hits being ads and clickbait - they all claim to be the best.

So I thought: let's ask the community, maybe they have good (or bad) experience with such apps. Or perhaps any tips in general.

What I'm looking for in an app:

• It does not have to be free, but I don't have a credit card (most of them are subscriptions). I do have PayPal.
• I like to learn left-hand right hand stuff.
• I'm really interested in theory on what "works" and what you can use to improvise (mostly my improvisations now tend to be the same chord and the same key)
• It's not an absolute must, but I would like to be able to read sheet music as if I was reading a book.
• I have a Midi keyboard, so I want an app that supports that.

So? Any suggestions from anyone?