Following The Brands on Facebook is obviously only part of the equation – you also need to be able to talk to other normal folks, and post your own stuff.
You can do this by setting up an account on any of the sites that still have feeds. If you’ve got a friend group you want to keep conversing with, it’ll depend on how frequently you like to converse – pick a fediverse instance if you tend toward chattiness, or pick Tumblr or WordPress if you tend toward writing a big post that people respond to. Or be like me, and be everywhere. (Including some silos, because Instagram/FB are still unavoidable for businesses.)
Ideally, you want your own site with your own control, but you can’t get that without paying for it (in money, versus in your data and privacy). WordPress will at least let you export your data later if you do decide to move to your own place, and many other platforms recognize WordPress export files because it’s so common. Fediverse sites let you change instances (including to a self-hosted one if you decide to go that route) and have your follows/followers exported, though your past posts don’t come with you. Your new and old accounts will at least point to each other though.
I haven’t moved my mastodon.art account ever, and clearly I should review my profile there more often. How was Poppi not listed as one of the studio cats? He’s been here going on two years now, and he certainly doesn’t allow me to forget his existence IRL: