"There is not much Garmin can do for you here.:"
Don't really agree.
Garmin could make their environment robust to bad data posting (Strava seems to have managed this).
Like really its only the data for a single users specific activity that should be duff (I've done enough development myself) - and at that point a user can pick that up with the 3rd party.
Garmin could scrap licence/certification fees (if there are any, otherwise I would be interested to know how much they are)
... but it seems if this is the case then Strava & Trainer Road are making it worthwhile for 3rd parties to engage while Garmin Connect isn't.
If Bkool metrics aren't integrated to GC fairly asap I'm likely to be looking at moving away from Garmin .
which will be a shame - since i've been on Garmin Devices for about nearly 15 years and I even like Garmin Connect (in most other regards).
Not really expecting it to get fixed alas.
Neither me. I do not believe Garmin is going to change their API policy. On my mind your best chance is asking Bkool to get it done, just like Zwift, Rouvy, Tacx and some others did. Well, Tacx is now Garmin, so that's a bit different story.