I think you have a great idea although there are definitely a few things that need to be implemented.
1. keep the piece color consistent. It changed 3 times when playing through this which threw me off and it was just a small nuissance without any benefits
2. expand the board. I think its great to start out on a 4x4 board but when there are more pieces it can get quite cramped, plus in a real game we play on an 8x8 so it is best to work on your intuition on an 8x8.
3. You might need explanations. you should probably give instructions on what to do. particularly with piece value, if you don't know which piece is more valuable than it will be difficult to understand why you take a certain piece and not the other.
4. Multiple correct solutions. there were some puzzles with multiple solutions.
5. Defended pieces. I think it would be great to implement a section where there are defended pieces that you are not supposed to take, rather capture a different piece.
6. Checkmates. Begginners should really learn all the checkmating patterns, whether it is m1,2,3 etc. having a good intuition for checkmates is super important and useful.
7. Seperate the sections. It might be most intuitive for users to have different levels or sections so they can choose what they want to practice (or maybe even a mix problem).
Overall I really like the idea and as you said it is just a rough idea, there is still a lot of work to make it an effective tool.
I'm working on a new kind of chess training tool for absolute beginners who are either too young or too impatient for conventional instruction. It's still a bit rough around the edges but the general idea is ready. Please take a look: https://www.prechess.org
Thanks!