ShortCat uses the accessibility API to put Vimium-style keyboard links on buttons and text fields in any app.
I find that Vimium works faster in Firefox than using ShortCat to click around websites, so I use both, but ShortCat technically should do everything (clicking-wise) that Vimium does.
I wonder if it has to do with accessibility API thread locking. I found a different extension I used to emulate an i3 style environment suffered when I used the Unity game engine. It ended up being limitations of the accessibility API.
This delay is configurable. The delay is there so you can actually type a bit before the UI pops up, and then the UI will be filtered to just your selection.
As I understand it, a payment system is in the works. I would gladly fork over some cash to support ShortCat. Looks like someone recommended Homerow, which appears to be pretty comparable to ShortCat, and it has a one-time purchase option.
Ha! I actually switched from Vimium to Tridactyl partly because I prefer the rough, snappy scrolling. It felt much more like the ctrl+d ctrl+u navigation in VIM.
I never started with Vimium (was using an even less known one), also in part because I find smooth scrolling disorienting. Also on Tridactyl now, once someone on here showed me the hintfiltermode, hintchars, and hintnames settings to get the old Vimperator behavior (which I also find so much better than any current defaults):
set hintfiltermode vimperator-reflow
set hintchars 1234567890
set hintnames numeric
Lets you type the words in links, and the hints filter down to only matches. If you go all the way to 1 match it automatically picks it, but as the hints filter down the numeric labels also reset - so there are no gaps betweeen the numbers and it's almost always between 1 and 5 to get the link I want.
I would typically do something like this - I'd press "/", search for an occurence, it navigates to one, if it's a link, pressing "go" - opens it in a new tab, "gb" - opens it without switching to it. I promise you, you'd love this.
i use i3wm so there are various keybindings you can use.
for mouseless stuff i use xdotool to move the pointer in 16 or 64 pixel increments using the keyboard.
if i could toggle the mouse pointer on and off i would.
Mouseless as well for navigating anywhere on the computer without a mouse -> https://mouseless.click/