From one arena survival game with dice based enemies to another, you got everything good about the formula!
I like the duality and chance of the upgrades, definitely gives that little dopamine hit.
Here are minor things that I would improve.
Adding a minor delay for the buttons on the upgrade menu (I started the game spam clicking, cause I didn't know you could hold shoot, and accidentally insta-clicked the choices without seeing them).
Make reloads automatic and take a moment, but maybe speed up when pressing R. Having to constantly press R to reload every time strained my hand pretty badly.
Fun little game, always a blast with an incremental action survival game.