The problem with keyboard navigation is that there seems to be no mature GUI keyboard-first UX concept. "Mouse things" are the way they are, because they fit the mouse-way. We need the same for the keyboard-way. Until then, there seems to be no design concept that can just be copied.
There is, whether or not developers follow it is a different story.
https://www.w3.org/WAI/ARIA/apg/practices/keyboard-interface...
>there seems to be no mature GUI keyboard-first UX concept.
I don't know about 'first' because I don't see a reason to privilege keyboard workflows over mouse workflows given how ubiquitous the latter is but Windows has had, for literally decades a 35 page Keyboard UI spec. They've put a fair amount of effort in applications being navigable in a consistent way.
https://learn.microsoft.com/en-us/previous-versions/windows/...
Top of my head:
- Tab to move across fields.
- Left-to-right, top-to-bottom focus.
- Space to toggle togglable stuff.
- Alt-Down Arrow to deploy drop-down stuff.
- Arrows to move around.
- Enter/Esc to accept/discard a modal.
Or maybe I misunderstand the things you call "mouse things".