Too late for me now... I am in the middle of a flat bar gravel build and it's my first disc build. I got an MTB groupset but couldn't figure out why the brake calipers wouldn't mount. After looking at the disc groupset I have for a road build I saw the difference between MTB & road calipers.
I guess the move would have been to get the brake levers and calipers separate but I wonder if anyone makes "flat bar" groupsets? I'm guessing they make them for hybrid bikes