You are contradicting yourself, you “understand that AdGuard has nothing to do with redirecting traffic” but it was in your routing question context and you have concerns about setting up container about that?
Regarding routing per host name on MT, search forum, you have some topics like http://forum.mikrotik.com/t/routing-traffic-for-specified-domains-to-a-different-gateway/146125/1 or open anoher topic for such question, it has nothing with Adguard or DNS in general, if we exclude DNS resolving from context for ROS address list (for linked topic solution), thats why I suggested in some above post to remove Adguard from ROS upstream DNS, to avoid filtering for ROS.