This looks really cool! My current setup is Firefox with VimFX[0] and an elaborate config.js, but when the NixOS package gets merged I will definitely try it.

For anyone wanting to stick to stock Firefox ESR, I highly recommend checking out VimFX.

0: https://github.com/akhodakivskiy/VimFx

The big downside of VimFX compared to Glide is lack of Firefox internal API documentation. I've had to dig through Firefox source code several times to find out how to do things e.g. wrangle tabs that would have been easy to do with the WebExtensions APIs. The fact that Glide makes these APIs available in the config file is the part I'm most excited about.