The build I played was missing some functionality as you stated upgrades weren't really implemented which was unfortunate. The game definitely needs some balancing, some runs feel really easy while other feel brutal and it depends on the boss ability and whether or not you were able to mitigate it.
More info on what things do would be nice, like are boosts permanent or temporary when it comes to items. Actually seeing the change would be nice as well, being able to visualize upgrades helps the player understand whether or not certain decisions are worth it in future runs.
That said it does show promise, I can see it being a really fun strategy game and you talked about already changing a few things that will really improve the game.
Thank you for popping into the stream!
Gameplay 06:28:52