Privacy focused personal zeroknowledge cloud things are needed.
I'd love to have a more elaborate version of Firefox Sync that worked across chromium (and I'd pay for it).
The obvious calendar, mail, etc.
I'd pay for a zeroknowledge hosted Berners Lee Solid service.
Do this stuff and I'll pay well for it.
Keychain support is the only reason I recommend Safari, because password sharing with iOS is so important.
On Windows it's a big mindshare problem. So I'm supportive of their marketing efforts.
Their best bet is to do affiliate selling. E.g. discount Dropbox subs originating from Firefox.
Don't focus on stuff that Google does well, like e-mail. Focus on stuff Windows does poorly, like OneDrive.
So you're right on the money with password sync. Basically nonexistent in Windows. 1password affiliate selling = A+.