The new versions of Firefox have almost the same plugin interface as Chromium. If you're satisfied with it, then why aren't you satisfied with it?
See what fellytone84 had to say about keysnail, here on HN, 4 years ago [2]: I consider Mooz's Keysnail Firefox add-on to be the most impressive keyboard oriented browsing tool. It's endlessly configurable, dotfiles in javascript--really nice to work with. For Chrome, the Vimium extension is very good, but recently I've been having a lot of fun with a similar, more configurable alternative called chromium-vim.
[0] https://chrome.google.com/webstore/detail/cvim/ihlenndgcmojh...
So while I do miss the old extensions, and disagree strongly with how they went about it, any particular thing that's available only on chrome isn't really because chrome is better. With a little push cVim could support both browsers.
There's also a menagerie of Vimperator alikes for Firefox: Tridactyl, Vim Vixen, Surfingkeys, Vimium-FF, VVVimpulation. Most of them have improved substantially since September 2017.
Disclaimer: lots of Tridactyl's jank is my fault.
Apparently support for doing gestures correctly would "break the security model" and the code would be rejected, so I'm going to disagree there.
You wouldn't say that the new train carriage, which only works on the Bosnian gauge and not on the Standard gauge (EU, US) "makes the experience better and better" even if they have free wi-fi, air-conditioning, plenty of feet space, leather seats, panoramic sunroof etc. You can't even use it, so all the extras are useless.
I took Chromium, found the perfect plugins, and never looked back at Mozilla, after 10+ years of using it. If it's broken, you can't use it, even if it's fast.