Transgay is rare: but it has almost 3 times as many entries as transhet here on Itchio: so please check out the collection and give those folks some love: https://itch.io/c/4614757/trans-dudes-in-gay-situations (It's the same for Transbian stories: almost 3 times as many as tf/m stories.)
I've found that sadly, a lot of these stories get ignored though ;o;
Even beyond Itchio, transgay stuff is plentiful and here's a starting guide: https://www.darkchibishadow.com/post/a-starting-point-to-finding-stories-featuri...
I hope you'll consider supporting some of the artists listed there!
You're also welcome to join the Trans/Queer jam to make more: https://itch.io/jam/transqueer-jam