I think the bit where the labels change is a pretty big differentiator, for things that are per-app.

Are you old enough to remember when PC applications came with templates that fit over a 101 key keyboard to show you what all the fn keys did? That's why very little outside professional tooling uses them for anything but system-wide shortcuts anymore. They're horrible for discoverability so unless you live in the app enough to thoroughly memorize them they aren't terribly useful.

As much as I don't care for the Hot Bar in general, it is far better for per-app shortcuts that are used rarely enough not to require (and thus develop) muscle memory. You'd need one of those OLED keyboards to do much better.