First off having seen you post on here for some time I’m more than happy to take what you say on face value and clearly your proactive. Also I’ve been in an environment that has bees tolerating and thriving with varroa without treatment so not a none believer
But I’ll stick with what I’ve said if tolerant bees are to be reared/found it will be the large breeding groups and associations that will likely be the source. Most of us that have been around awhile will also happily agree there’s a management route to controlling varroa as well, if your inclined and have time and resources. In regards to open mating I agree with the issues you mention but again it’ll be those larger groups breeders with access to II, truly isolated sites or proper drone flooded areas. But you answered that yourself flagging the open mating issues. So I’ll stick by the fact if vsh/tolerant bees are to become accessible it will be those larger guys not the 7 hive owner
that provides them. I truly wish you the best of luck and many happy hours with your bees. Ian