Well: yeah the formula menu was a "last development sprint" edition to the game, which is why there is no gamepad controls. Although retrospectively this is a bad excuse, since it should not take too much effort to implement it. Although I must admit that I have no experience on how to make Unity-UI work with gamepads.
Also: it depends on how you define Metroidvania as a term: so going with the Jam-definition it is: items/abilities hidden behind or in locked areas. But I do understand that the player itself doesn't really get more powerful directly, but implicitly.
Still: thank you very much for playing my game and the feedback! If you have any idea on how to make it more metrodvania-ish please let me know! :)