Some kind of plugin manager/installer is certainly something that will get added to OBS, probably sooner than later.
The AMD AMF encoder is still preset in OBS, it just requires somewhat recent GPU drivers to work (19.7.1 minimum, 19.9.2 or newer recommended)
Platform-specific stuff kinda sucks but it's the nature of the beast.
Unfortunately, at some point they seemed to have removed support for the AMD encoder used with my old GPU, so I can't enjoy the recent software updates until I update my hardware.