In my case, the only iPad is the cheap secondhand one. It would still be nice if I could "borrow" it for the weekend without having to sign in to every service

In my case, the only iPad is the cheap secondhand one. It would still be nice if I could "borrow" it for the weekend without having to sign in to every service that is already tied to my Apple ID. I don't disagree with you in general and it is what I recommend to others with the same issue... but the issue is completely unnecessary since (however many generations ago iPad hardware stopped struggling).