The issue is that HOME continually changes the HOME tracker. If you have a dump of PK8 files, migrate them through HOME and into SV, you can't just do a lookup on the trackers and try applying their corresponding moves into their SV instance, because the HOME tracker is different for both. You'd have to use a heuristic (combining PID/EC and other details) to try and 1:1 correlate them, then run an operation to try setting those moves legitimately.
It's moreso for people looking to make a plugin. That's the name of the class you'd replace with whatever custom implementation. PKHeX's source code is available on GitHub.
If your goal is to retain legitimacy, then you have to transfer them legitimately via HOME, which won't use PKHeX's transferring logic. You'd need some other bulk operation that is triggered from a box / folder, completely separate code from what PKHeX currently does. Then you would likely want to audit to see which ones were able to have all moves migrated, which had none, and which had a few. Learnsets change between games, and meta movesets are not always the same. It's not something I'm interested in doing since it's incredibly niche (how many people would actually jump through the hoops to get bulk moveset copying?).
You (or someone else) is more than welcome to make a plugin that adds a button to do all that, but I don't see it as necessary to be in the main program that is distributed & maintained by me.