Personally it's the integrations. I have a Chromebook, which integrates with GSuite, and integrates with Android. I can manage extensions, permissions, etc, all from there. This is important since I use this Chromebook for work, but it would be cumbersome to run Firefox and Chrome simultaneously.
With Firefox I get just-a-browser, and I need more than that. If Firefox had a way for me to manage the browser across devices it would be more viable for me.
First, you can sync your browser with your Firefox account, so this is I guess what you want?
Second, for the Google (Gsuite, Android) integration, you could just use a work browser (aka Chrome).
Third, if you use all that Google stuff in your private life, I don't really see why you would be worried about Manifest 3-related privacy and ads/tracking matters anyway. I mean, Google already has your data.
> First, you can sync your browser with your Firefox account, so this is I guess what you want?
Maybe? Probably not though. For example, with GSuite I can manage the settings via the web UI and then have policies that enforce that those settings are verified correct.
> Third, if you use all that Google stuff in your private life, I don't really see why you would be worried about Manifest 3-related privacy and ads/tracking matters anyway. I mean, Google already has your data.
I opt into Google having my data, but I want to be able to opt out of running arbitrary content in my browser. uBlock and uMatrix give me that, Manifest v3 takes that away.
It may be due to my workflow; I simply hit a key combination to either open my personal profile or the one for work, for example.
Nothing fancy... The -P option for Firefox along with the usual key bindings for my window manager