Might be late to the party, but I just discovered you can do this. Super simple and easy to do.
After having a read of the linked page, I backed up and just used this option:
https://wiki.archlinux.org/title/Profile-sync-daemon
Installed, created config, and enabled service:
systemctl --user enable psd.service systemctl --user enable psd-resync.service
I definitely notice an increase in speed and less SSD usage should hopefully increase lifespan.
I’m sure there would be options for alternative distros, anything using Systemd should be able to use the daemon.
Are you implying the tabs backups are not written into the profile folder? Because think 10 - 20 GB a day is still something to be convened about. https://www.servethehome.com/firefox-is-eating-your-ssd-here-is-how-to-fix-it/
I have used Firefox in ram for a couple of months now without problems and am pretty happy with it.