you may not even have to change to another browser or fork, please have a look at some designs in https://trickypr.github.io/FirefoxCSS-Store.github.io/
select a design and follow the page, and you shall find the instructions (usually just downloading/pasting userChrome/Content.css)
and for scrolling tabs, if your problem is very small tab size, then try changing browser.tabs.tabMinWidth in about:config
Floorp, I use it and I love it. It's especially great for Opera refugees, it has workspaces and stuff. Soon Firefox will support tab groups natively, and then Floorp will be perfect. It's a Firefox fork though.
Tab groups and non-independent tab muting (seems like it was domain-specific rather than tab-specific last I tried) are the two main things that kept me from switching back to FF as my primary browser (still use it for DTA, for example, but DTA got a big nerf back during the major extension overhaul, so that was a letdown). Tried some extensions, but none really worked in a way I considered usable and didn't want to just keep trial and erroring through them given I already have a browser that functionally meets my needs, even if I'd rather not be using a chromium browser.
If native tab groups work well enough, I'll probably give it another chance.
I sometimes just need to mute something for a second that I'm otherwise listening to. Or I'm switching between multiple sources, and don't want like 3 or more playing at the same time.. usually all on the same domain. I don't want to have to actually go to the tab and mute it. I'm frequently muting and unmuting things that way to the point that even if its the only source of sound, I still mute by tab instead of just turning my computer volume off sometimes out of habit, so its a deal breaker.
I think this just says more about the perils of embracing untreated ADHD than the internet itself.