citation backing up your claim about oral prog not sufficiently raising blood progesterone levels: https://transfemscience.org/articles/oral-p4-low-levels/

However, newer studies using more accurate blood tests (immunoassays with adequate purification and mass spectrometry-based assays) have shown that 100 mg/day progesterone—with or without food—achieves very low peak progesterone levels of only about 2 to 3 ng/mL and average progesterone levels over 24 hours of only about 0.1 to 0.6 ng/mL

In accordance, oral progesterone has often shown only weak progestogenic effects in clinical studies.

While the progesterone levels with oral progesterone are apparently sufficient for endometrial protection in cisgender women, they are unlikely to be adequate for desired effects in transfeminine people. For these reasons, transfeminine people and their clinicians may wish to avoid oral progesterone if the aim is therapeutic progestogenic effects. Instead, non-oral forms of progesterone with greater bioavailability like rectal or injectable progesterone can be used.

Personally, I only take prog to help me sleep, and anecdotally I have better sleep with rectal administration than oral. I also notice stronger libido with rectal administration than oral.

My dose is 100 mg - 200 mg per night, averaging 100 mg / night, and I don’t take it when my estrogen is low, so on a weekly basis I cycle my prog taking it only half of the week in accordance with my injected estradiol valerate metabolic cycle (half life of roughly 3.5 days, I take prog as my estrogen blood levels increase and peak, then stop once E blood levels start to drop).