I desperately wish they'd give me the option to pay for Firefox Sync. I would, genuinely, pay for that every month. I get a massive amount of value from being able to throw tabs from my laptop to my phone and vice versa, and have everything synchronized, in a way I trust.

Did you mean people could sync and not pay? Few people would pay. Or did you mean people would have to pay to sync? The market standard is free sync.

You can give money to Mozilla Corporation by paying for Firefox Relay, Mozilla Monitor, Mozilla VPN, MDN Plus, or Pocket Premium.

A browser can't sustain itself. That's kind of the core problem.