[yjftsjthsd-h]

I'm sure GUIs can provide keyboard navigation and such, but it's not clear to me that this was common. Unfortunately, I'm working from anecdotes, so I can't tell, certainly not this far in the future, what the relative average quality was.

[int_19h]

This was very common. For starters, pretty much every UI toolkit provided keyboard navigation between widgets with no need to do anything special. The common QoI problem there was that developers often didn't set tab-index correctly, so if you tabbed through the widgets, the order would be wrong (i.e. not following the screen layout). Visual designers often provided linters for that.

Then there were the shortcuts to immediately activate the specific label, button etc. On Windows, these showed up as underlined letters up until XP (in XP and later, you have to press Alt to see them). Again, as a QoI matter, devs could forget to put them in - but it was really easy to do, and if you didn't, the lack of underlining was actually kinda noticeable. Most apps had them.

This kind of stuff was even codified, to some extent: https://en.wikipedia.org/wiki/IBM_Common_User_Access