Keen is definitely a word but when used to describe a person it’s often a bit of a backhanded compliment… you don’t really want to be keen.

Saying "I'm keen to do x" or "he's keen to do y" is a fairly common normal usage but having said that, wouldn't normally be my first choice of language as a millennial, maybe does sound a bit old fashioned

Right, as far as live exposure, I associate its usage with UK/AU/NZ expats in my western US, academic R&D microcosm.

Yeah, I guess I can also see it as more of a Britishism (etc.) currently.