Though this is no confirmation of any sorts, this fits the description of Dr. Bill Foster, known in the Marvel universe as the hero Black Goliath.
Considering the casting requirements for the role, if this is indeed Dr. Bill Foster, then it’s likely that he’s a retired hero and just a former peer of Pym.
Black Goliath was introduced for the first time as Bill Foster in Avengers #32 in 1966 as a brilliant biochemist and peer of Hank Pym, the original Ant-Man played in the 2015 film by Michael Douglas.
In fact, it’s possible that in this version Black Goliath doesn’t exist, and Foster is just your everyday average genius in the MCU.