Oh, almost forgot: any messing around with sex hormone levels puts you at risk of depression. That's big side effect #3 (though again, many people don't even notice it).

it's not estrogen where you would expect breast growth (and can't count on any particular changes to sexual function anyway), it's inhibiting conversion of testosterone to dihydrotestosterone which could have that effect, much like you could spontaneously develop gynecomastia without intentionally fiddling with your hormone balance. calling it unsolved sounds a lot like calling the very many conditions with medications that have more likely and worse side effects equally unsolved.

Finasteride is less potent, but is normally recommended for cis men; not sure why. Theoretically, I'd expect dutasteride to be the better medication (and https://doi.org/10.2147/CIA.S192435 bears that out) if you can get hold of it.

I'd have thought finasteride and dutasteride weren't safe to take if there's a chance of you getting someone pregnant, but https://www.nhs.uk/medicines/finasteride/fertility-and-pregn... says it's fine, actually. https://doi.org/10.4103/0974-1208.86093 goes into more detail on that. (I'm not aware of any other impacts on fœtal development, only the intersex condition mentioned in that article – note that the backdoor pathway described in https://doi.org/10.1002/dvdy.23892 also requires the 5α-reductase enzyme –, but I'd still advise caution.)