Fwiw I ordered one from hifi express recently and it came with the newest firmware (1.7), so I wouldn't worry about it if you buy a new one.
I have no trouble driving a pair of HD 660s with mine, even with EQ.
The speakers will put any analog input through a A/D stage so any GLM room correction etc can be applied to the sound - I imagine the crossovers are digital as well.
Airpods (and the airpods pro/airpods max) and some other bluetooth headphones already do EQ the sound
Outside of bluetooth though, the current solutions are mostly aimed at studio/pro use. Audeze have their Reveal plugin, and there is also Sonarworks for other brands.