Thinking about the queer characters in ASOIAF. There's a few in the main series, like Loras, Renly, Taena, Nymeria, Lyn, and probably a few others I'm forgetting. I sort of wish there were more queer women in the story. Dany and Cersei have same gender relations but it's ambiguous as to if they are bi or not (I like to headcanon them as bi but that's just me). We have mention of Nymeria being "abed with the Fowler twins".
Fire & Blood had a lot of queer women; Rhaena, Elissa, Tyanna, Jeyne Arryn, Black Aly, Sabitha Vypren. It was pretty refreshing to see more visibility of queer women there, and I hope, even if my hopes for House of the Dragon aren't high, that they do a better job than Game of Thrones in that regard. I especially loved Rhaena and Elissa, they were both incredibly compelling and fascinating characters.
One area I think ASOIAF & GRRM could possibly improve on is trans representation. Of course Brienne, Cersei, and Arya come up as examples of gender non-comformity that could be seen as transgender identity, but they don't reject the concept of womanhood so much as gender roles. When we hear about MtF crossdressers in this universe, it's often not very flattering, and usually some sort of fetish or kink.
We have a Lannister monarch who was mocked as "Queen Lorea" and dressed in his wifes clothes when visiting the sex workers in the docks of Lannisport. Racallio Ryndoon was also said to have dressed in women's clothing, pretending to be a female prostitute, and was sometimes called "Queen Racallio", but given everything else we know about him (having fetishes with pregnant women and having his wives beat him), it seems like it's just another fetish of his.
We also have a sex worker in Braavos Arya reports on in ADWD called Canker Jeyne, who (at least in my mind) probably is trans, but again, it keeps on with this rather unflattering image that MtF people are all doing this as part of some fetish or satisfy other peoples fetishes. And in the case of Racallio, it's made to make them seem more "exotic" and "wild". Meanwhile for FtM crossdressers, it's mostly used as a disguise of sorts or a rejection of traditional femininity, rather than any sort of solid core identity.
We do, however, have the Jogos Nhai, who allow AMAB people to live as women, or AFAB people to live as men, to the point that they will shave their bodies and perform the tasks expected of the gender they are now living as. This is reminiscent to some historical societies, such as the galli priests of Rome, who worshipped Cybele and Attis, who were castrated, whore feminine clothing, and referred to themselves as women.
There are many other societies and cultures that, may not have had the concept of transgender identity, but definitely a less binary view of gender identity that could be seen as transgender. For instance, there is the concept of a third gender role in some Native American peoples, like the Navajo nadleehi and the Zuni lhamana. Regardless of culture, there were some historical figures who were transgender regardless of cultural traditions. The Roman Emperor Elagabalus was said to have delighted in being called a lady, dressed in women's clothing, and apparently went around asking people to perform sex reassignment surgery for a large sum of money. There is also Chevalier d'Eon, an intersex transgender woman who fought in the Seven years War, and lived as a woman for 33 years until her death.
The point of this being; there is a sorry lack of trans representation in ASOIAF, and it is mostly relegated to fetishes or kinks, which, as a trans woman, doesn't leave the best taste in my mouth. It doesn't make me hate the series at all, but it's a little disappointing as someone who would like to see themselves represented in a story they very much like.
This is why I have taken matters into my hands and decided to write an epic fantasy story with the main character being a trans woman partially inspired by Elagabalus.