Or you could just do a quick inventory of which of those groups / are still important to you. And then sign up again using a different device / email address. Along with, of course, a totally fake user name. And (slowly) sign up again for those pages.

Which I guess would against FB's terms of service, in theory. But fuck that. They certainly aren't honest and above-board with you -- there's no reason you "owe" them any particular degree of honesty in return. Just use them for what you need, and let them (and their expected monetization off the minutia of your inner life) sod off otherwise.

As you with with, you know, any commercial product.