so whats the big deal?
well, according to most studies done, progesterone is assumed by many endocrinologists to stop sex drive in women, if you look online youll find a few womens health blogs that suggest otherwise and its about "balance" but many say it firmly is about shutting off sex drive.
https://www.futurity.org/progesterone-says-%E2%80%98stop%E2%80%99-to-female-sex-drive/
And yet the prevailing result of these first two polls shows a majority of transfeminine people who had low sex drive, found it increased when they started taking progesterone either rectally or orally, to pretty much the same degree.
Taking progesterone orally means the majority you take doesnt end up in your bloodstream, instead it gets broken down by the liver to allopregnanolone (allo). Rectally use we know a far higher amount of progesterone ends up in the bloodstream and lasts at quite high levels through the next day or and either little or none of it is turned into allo.
Although the results here are a small poll of 164 people we can atleast hypothesise that this shows not actually a lot of progesterone that is required to induce this response, and the stark similarity in results suggest that allo does not play a key role - even though for some it can induce a dopamine / anti-anxiety / sedative effect.