Maybe someone is running into the same problem, so here are my conclusion after extensive search on the internet.
For the Max 3, I couldn't find a cover + keyboard. I think the best choice would be to only get a fix keyboard, and I would suggest this one:
https://www.logitech.com/en-us/produ...oard?crid=1221
For the Note 2, I think that this next one would be a pretty good choice:
https://www.logitech.com/nl-nl/produ...case?crid=1221
If any of you knows a better solution (or an alternative solution, or even feedback on the solutions mentioned above), your feedback would be very much appreciated
Based on this I will probably give the Max 3 back and take the Note 2, as portability is kind of important for me.
ps: by the way, apparently bluetooth is much easier to find that usb type C, and do not use too much power, so I think getting a bluetooth keyboard is a better way to go than trying to find a usb keyboard. That's why I changed a bit my search.