Hey, thanks a lot for the report and the photo, it really helped!
Both things are in the next update:
Resolution scaling: the game now fills any screen size or aspect ratio, 4:3 included, with no black borders. On small screens like 640x480 it starts in fullscreen automatically and uses the whole display at a crisp 1x.
Directional Aiming: there's a new option in Options → Controls → "AIM WHERE YOU WALK". With it on, you attack in the direction you're moving, so you don't need a mouse or a right stick. The wand's arcane circle lands a few steps ahead of you, in the direction you're walking. All the keys can be rebound on the same page to fit your handheld's buttons.
Let me know how it runs on your device. I'd love to hear if anything else feels off on handheld!