https://f-droid.org/packages/de.tnmgl.ntodotxt
I have used flat txt files and also ntoodotxt for other stuff. Sync them all with syncthing.
You can spend real-world money on a virtual currency called San Van Bucks, which in turn is used to buy cosmetic items.
I hate this but if it’s just cosmetics and the game price is fair I’ll be ok with it. I know the price is going to be a full on AAA release and they will still cram this into it… but I can hope.
https://en-americas-support.nintendo.com/app/answers/detail/a_id/48058/
Pretty sure number 1 covers it, but I’m not a lawyer.
Gone back to working on Monster Hunter Rise with my son.