Possible to Implement Baseband OFDM on Microcontroller?
OFDM is just math; an OFDM receiver is just an algorithm. As a microcontroller is a universal computer (i.e. equivalent to a Turing machine), it can execute any algorithm. So, the answer is yes.
Whether or not it is performant enough / has enough memory for the specific OFDM system you have in mind is something nobody can tell you without knowing exactly what kind of OFDM system, what performance bounds and what microcontroller you have in mind.