I tried MK-2866 (ostarine) quite some time ago for five weeks at 20mg daily, with bloodwork done beforehand and afterward. No suppression. A lot of the anecdotal evidence indicating ostarine suppresses normal HPTA function is the product of ostarine cycles lasting 12 weeks or more, at doses higher than what I used.
But that's of no concern to you, because you're on HRT. So ... honestly, man, it's nothing that great. I mean it's fine, it possesses no inherently problematic characteristics, but it's certainly no anavar. Or even winstrol for that matter. If you're on HRT, and you use this forum, I can probably safely assume you've cycled before, yes? If that's the case, ostarine isn't going to knock your socks off by any means.