This should be fucking obvious but an argument I just went through on Twitter (gods I really should just not get on twitter) tells me that even left-leaning people for some reason sometimes think they are owed this information simply because they are interested in flirting.
Transpeople have no obligation to out themselves. even if you have or are going to kiss, or date them.
To think otherwise is to assume you are owed knowledge about their body. To get upset after they do tell you is to assume you were entitled to continue the relationship, or that they were trying to manipulate you.
If you have hangups that would prevent a relationship it's on YOU to be upfront about them or to accept the potential disappointment with grace.
I can't speak for everyone but I suspect most absolutely would want them to know as it can both be relent
if we get conformable enough / know them well enough to trust them with that information.
Trans people put a target on their back every time they share who they are. tell the wrong person or let the wrong person overhear and we can get anything from hatemail to fired to much worse. and even with those who take it relatively well the information can entirely change how they treat and interact with you.
if we find someone to peruse a relationship with, and learn enough abouttthem to trust them thenthey will ffind out.
thats said. for more casual friendships or can be entirely irrelevant information. we don't have to be and often find want to be defined by being trans. Being on the autism spectrum can be a bit different because it's not always something that can go unnoticed. but if I'm just making friendsiI don't needto sshare something that personal when it hasssuch large risks.
tldr; it's a deeplyppersonal and often risky thing to share that is nnormally irrelevant