TRAs are just as vicious towards trans people who don't conform to their narrative, as they are with non-trans people. Creating a trans support group that wouldn't support the official trans orthodoxy would be a risky endeavour. To my knowledge, there doesn't exist such a group in my country, for example. I looked for one recently, and didn't find any. Literally all the support groups parrotted the TRAs' lines, with no deviations. The only collective which goes against the grain is so small, it's literally a couple of people, so way too small to establish any kind of support group.
Those groups have allowed a sub section of extreme transgender rights activists to control the public discussion for too long.
It's the other way around: the support groups are built around the TRAs, or at least around their credo. Makes sense, too: imagine I created a support group whose mission would be, "To help people questioning their gender identify what's working wrong in their head". Not only would nobody want to join such a group, but I'd be attacked for open transphobia by the TRAs. My group would be dead before it even had a chance to exist.
So, yeah, basically, no trans support group fights the TRA narrative because no trans support group can exist if it fights the TRA narrative. It's frustrating, and I've been trying to find a fault in that circular logic, but so far I'm stumped.