It certainly would be but looking at the options tells me that they're hooking into MacOS's widget libs and on Linux there's just so many. What I get by with to go mouseless is Tridactyl for Firefox, warpd for when I need a pointer, and when I absolutely, positively need a mouse, mouse emulation on QMK keyboards never fails me. I only need it these days for dealing with MacOS outside of my Linux VM. I also use keyd in order to remap keyboard shortcuts.

https://github.com/rvaiya/warpd https://github.com/rvaiya/keyd

Why in the world are those links side by side?

There's Vimium Everywhere, a very recent tool for Linux of mine. I don't know of any other. https://github.com/phil294/vimium-everywhere

On linux, you can just install one of the DEs that are keyboard driven. Rat poison is one. I used that with Conkeror (a fully keyboard driven browser with emacs keys) for a long time.

There's also good old i3, which has vim-inspired key maps by default iirc