Browsers shouldn't have accounts to begin with.
*) Or whatever the real reason was. It was about time Mozilla started to have management issues so I absolutely won't be surprised if the goal was to "become an ecosystem" or "gather a userbase" (or whatever is management speak for forcing people to sign up).
How is that not still an account? What definition of account are we working with here?
You used to just open two Firefoxes, start sync setup on the one, copy (or scan) a code to another - boom, done, they're talking to each other.
Other options might be to have that personal homepage on a non-public machine (e.g., on your home or office LAN), behind a VPN, and/or password protected.
Another practice from days of yore was to export specific bookmarks and transfer those to other systems. This is indeed cumbersome with mobile browsers (I'm not sure these even offer bookmark import/export ... Looks as if that's synch-only for Firefox/Android, which is disappointing.
Linkding: https://github.com/sissbruecker/linkding