I get a solid rush of euphoria when the group I dm for uses they them pronouns as they talk about me. I'm only out in some spaces at this point, so it feels great having a space where things don't need to be explained or justified.
Shaving my face gives me a lot of euphoria. I don't have full on facial hair yet, but shaving off the peach hairs and staring at my face in the mirror covered in shaving cream is a good feeling.
OK I'll name some even though I'm actually talking about cisgender euphoria here, not to offend anybody. I'm a cis gender male who is gay, so I hope that there is space on this discussion for people who are openly cis.
What gives me great euphoria is knowing that I'm happy being a male and I rejoice in a feeling of masculinity overall. I'm attracted to males because of my own maleness - and it's all about hypermasculinity for me. Being gay has nothing to do with having female traits, but I relish and revere female traits also, though I think the labels are out of date and out of touch.
For example, I love to cook, and paint, and write, and hike and play piano. Some people (in the past) have equated those to feminine characteristics, but I say, no they are just human characteristics and amazing experiences. I'm not gay because I'm attracted to the "feminine," I'm gay because it is manly to me and much more honest than pretending I'm 'straight.' Masculinity to me is as much about honesty as it is about power or anything else.