I had a debit card (activated) that I didn’t use. After some time, they closed the debit card (not the account). So if you don’t activate yours, nothing will happen.
But now, I’m getting a debit card again from this bank (like yours, a small account to pay specific things). I plan to use the debit card on privacy.com to obtain virtual credit card numbers for certain transactions. I’m just trying it out to see how it works, and I don’t want it attached to my main bank account.