This is a major drag. I rely on Firefox and Thunderbird for all my personal computing (Linux, MacOS, Windows, everything other than iPhone/iPad where I use the default Apple apps) and have done so since the demise of the Netscape suite.
Not to mention that Firefox and T'bird are the default applications in Ubuntu and other Linux distros.
Geez Louise, this sucks. All the alternatives are worse in one or more significant ways. So I don't yet have a plan.
I feel you, dawg.
Trying BRAVE browser again, which also runs on Linux. Downside: It’s Chromium-based, but (upside) is still more private out of the box than Edge or Chrome.
I can’t vouch fof,it yet, but thorium browser is supposed to be very secure and very fast. But I use thunderbird too, and like it about the best- I’d hate to lose it-
I use Firefox too - hope you find something better... (and share with the rest of us...)
Thanks dayglored...