IDK how Floorp could escape my attention for so long, I only recently started to hear about it. Today I installed it and only used it for a couple of hours and I'm impressed how good it is. It's a very promising browser that I already started to like more then Firefox and easily beats all of the other ones that are based on Firefox. The other one that I like is LibreWolf with it's very sane default settings plus it came with the only extension that I ever need with UBlock Origin out of the box. I keep both of them on my system since they are different enough.
It has more settings it's comparable to Vivaldi in terms of customization while still being based on Firefox.
I like that I can finally use vertical tabs without extensions, that being the only way I could still have vertical tabs while I used Firefox.
Under the settings I discovered that web apps are supported, I tried out with installing one web app, the only thing is this feature is still being experimental in Linux and Mac, while under Windows it's recommends to enable it. The only thing that's a bit disappointing about the web app support is whenever I open the web app that I installed are only starting up after the browser opens before it, but I'm still happy to see web app support in a browser that based on Firefox.
Overall Floorp is in my opinion the best Firefox based browser, I definitely keep using it.