I thought it was going to be a huge hassle (I too imagined I had hundreds of accounts), but for me there were less than 30 accounts I actually cared about. Basically credit cards, banking, airlines, government services, social accounts, FAANG accounts, and domains/hosting. Annoying, but only took about an hour and a half.

The rest that are non-important I'll just let languish in the Gmail account, assuming I'll be able to go back and get them if needed, yet, also not being heartbroken if I get screwed by some faceless algorithm like OP.