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Definitely agree! I don’t know how easy it is to implement Material You into apps, but I love the look. This may feed into a conversation that was being discussed last year by @darcese about theming and colorways. I think by adopting Material You, Firefox is seen to be keeping up to date with developments, adapting to new technology and, most importantly staying fresh. Once you get used to curved, translucent apps, everything seems old, even when Firefox is actually kept up to date on a regular cadence.
The icon is a no brainier, no one wants a mismatched icon when all the others are themed. I think the Firefox Nightly app does this, I’ve got it on a Samsung Flip but I’m not sure if this is a Material You thing or just a Samsung OneUI that’s doing its own thing and it feels like the latter.
It is already in development. Currently available on Nightly and Beta. Should arrive in release Firefox too soon enough.