Whether or not THC affects thyroid hormones, weed use does not show up on a blood test for thyroid function.
I don’t know where you live or the relevant laws, but you should have confidentiality with your doctors and you should not have to hide any drug use from them.
I don’t have anything especially helpful to share, but maybe it’s not so widely known that anyone can run their own ActivityPub instance and avoid some of the collateral damage caused by other admins.