See, I like this a lot. Because one of the problems, as others have mentioned, is that the feeder pools for head coaches lack qualified minority candidates. This could encourage teams to hire and develop more PoC coaches at the lower levels, which in theory would trickle up to the head coach ranks eventually.
It's similar to the situation with black quarterbacks. Over the last 10-12 years you've seen a couple of black quarterbacks who have succeeded with the right coaching around them in the NFL. More importantly, those players inspired young black athletes to aspire to play QB, and the smart coaches realized that there are talented guys who are capable of playing the QB position. So in the last decade you've seen many more black starting QBs at the high school and college level. Of course that eventually made its way to the NFL, which is a copycat league. And now in 2020, the "elite tier" of NFL QBs includes four black guys and Drew Brees.
So anything the NFL can do to build up the downstream talent pool of minority position coaches, the more likely it is that we'll see PoC in head coach roles in the near future.