Shimano MTB levers with Shimano flat mount road disk brakes (hydraulic) Can you use Shimano MTB levers with Shimano flat mount road disk brakes (hydraulic)? Cheers
Yeah you can do that. Just make sure you use a new olive and insert pin.

I have seen it done on a self build frame of a guy as the wanted to integrate the brake as much as possible in the rear. You can follow the link and use and use a translator as it is in german.

https://www.mtb-news.de/news/2018/12/20/bike-der-woche-suit-1-eigenbau/