I don't know what you're asking for exactly or why me, but I suppose I have an explanation as to why there's so little real life trans porn where the trans girls do the penetrating.
If we're talking people with bonafide dysphoria, well it's just that it makes their dysphoria worse. The condition is really horrible to live with, constant hormornal imbalance, (even before hormone treatments) growing up with a wrong sense of how you're growing & what you are physically supposed to have, (lots of ghost organs, stuff like that) even without any external input, dysphoria causes spikes & interference with the dopanine & cortisol activity in the brain, which quite literally causes physical pain.
Trans women or just women who do enjoy penetrating are either more the dominating types or are just the odd ones out.
You're going to have trouble finding them, in general & even less some who are willing to do the penetrating & even LESS who would do porn of that.
There's a few tho, like Miss Poizon, among a few others.
TL;DR:
Simply put, it goes against their nature.
Just as it feels wrong for most men to be penetrated, it on average feels wrong for most women to do the penetrating, & therefore it feels much worse for most trans women, who struggle psychologically with not being "womanly" enough throughout most of their lives.