ARC pay fees in name of another account

Yup, the idea is to group all the TX that you want to pay in the same group, and set the fee on the app call = to the group TX size. Then all the other TX in the group will have fee = 0. That is the overall idea.

ARC proposal for soulbounded tokens

Great, that’s amazing.

I think I was not clear with my idea, I hope that this image clarifies the model.
I think there is not a possible attack. Furthermore, I prefer if possible to avoid smart signatures.