You can move back/forward and refresh, auto-hide certain buttons like downloads, add items to the "overflow" menu, toggle full/compact mode, toggle title bar, toggle a "grab" space...there are a lot of options.
They've also added proper support for light and dark icons for plugins. So now buttons like 1Password don't stand out with a dark theme.
To me it feels like a return to the level of customization I'd gotten used to in older versions of Firefox. And FWIW, this is what mine looks like: https://i.imgur.com/seJZeg6.png
It's like Mozilla is deliberately committing corporate suicide with these hasty feature removals.
It's coming. He has started. You can help by becoming a patron.
Woah!! I didn't think it was possible but...download acceleration post 57?