Even though I'm taking estrogen (and spironolactone) I'm still taking finasteride. I think just it's neat. I'm surprised it doesn't get used as much in gender affirming care.
Obviously it's can't be a sole anti-androgen as it only blocks DHT, but like women trans and cis are meant to have some testosterone if only for energy, libido etc. I think it makes sense to have the finasteride there to sweep in and block the DHT part that only have negative effects (hair loss on scalp, increased facial and body hair, prostate enlargement). It's actually prescribed to cis women who are losing hair or are hirsute, a demographic with a lot in common with some trans women.
The major side "negative" effects are reversible (1:100) and irreversible erectile dysfunction (1:10,000) which is a YMMV and breast growth
I pay 20 AUD for 30x5mg tablets, that I quarter, meaning I have 4 months supply at once and it costs me 5 dollar bucks a month.
Also seems like it has relevance for Trans Men who don't want hair loss from testosterone. IDK.