Wow, thank you for all this, it's a treasure trove of ideas!
You're welcome. You've got a concept nobody's ever done before. This is a brilliant take on the genre. It's very exciting.
As you know, Vampire Survivors has different ways of implementing stuff like attracting coins and exp that's on the ground. In that game, you just walk over the orb power up, and it sucks everything up. Or you buy the item that makes you attract stuff.
Since you seem to be using an alternate upgrade scheme, you could attach these abilities to towers.
Like having a very fast thief who goes and collects stuff for you. They'll run over EXP and keep a portion to upgrade themselves, and the rest goes to you. Coins too.
Your tower system could let you achieve many of the common effects for this genre in ways that haven't been done before. In ways that fit the identity of your game and the universe it takes place in.
Also, the mere fact that you actually have teammates in a genre where it's one against endless waves of enemies is astonishing.