It's not a clean experience and I wouldn't recommend it to anyone non-technical but I use this approach and it works fine, at least for the extensions I care about. There's also the caveat that you're running Firefox Nightly which usually is fine but has had big functionality bugs. I'd keep another browser installed as backup.
https://blog.mozilla.org/addons/2020/09/29/expanded-extensio...
It's not a clean experience and I wouldn't recommend it to anyone non-technical but I use this approach and it works fine, at least for the extensions I care about. There's also the caveat that you're running Firefox Nightly which usually is fine but has had big functionality bugs. I'd keep another browser installed as backup.