As (yet another) cis guy, I can’t speak to what you’re going through but I hope this story gives you some food for thought:
When I was younger I took Savate classes - French kickboxing - and there were a total of three people in the class. Groups were similarly small at the few places we would compete with, so everyone competed against the others in their weight/skill brackets regardless of gender. At one meet a guy mouthed off about having to “fight a girl” and our instructor turned to us and told us to watch closely, because the dude was about to get his ass handed to him. He was right, she beat him handily. She beat the next two guys she was up against as well, but those matches were closer and far more interesting to watch because at that point nobody was holding back; it was truly competitive.
On the ride back our instructor spoke to us about how that first guy had forgotten that these sports aren’t just brute physical strength - speed, flexibility, awareness, wits, and adaptability are every bit as important. And that any person who judges their opponent before the match begins doesn’t have the skills required to progress very far in a competition.
So whatever you end up doing, I hope you have a good time and kick some ass, though since it’s BJJ maybe I should say flip it on them.