technically yes, between yoshiki and hikaru you could say that. But its being clearly said that its a one sided crush, I dont know if this is supposed to be a fact or if this is from yoshikis perspective. And the new 'hikaru' doesnt feel emotions the way humans do. Appearently Unuke-sama has no emotions, no personality nor a sense of self, but simply imitates their hosts. But I'm not even sure I can believe that. If someone appearently has no sense of self or emotions, why would they seek a place where they can belong? Why would they ever feel lonely? Why would Unuke-sama say that they love Yoshiki? This is very confusing. I'm not complaining about the shounen ai tag, even if there isnt an actual relationship, this story is pretty intriguing and sad.
In earlier chapters, "Hikaru" said that he likes Yoshiki multiple times, hinting that it's based on Hikaru's memory/body and not "Hikaru". I don't think we can completely deny the possibility of Yoshiki's feelings being reconciled. Hikaru was a very secretive and private person, after all, and didn't wear his thoughts and feelings on his sleeve.
“Is the shounen-ai in the room with us” Yeah it is, shounen-ai isn't simply just romance, it can be a romantic or emotional relationship between two male characters. So yeah it's still Shounen ai, There is an emotional relationship between the two Mc who are boys with romantic underlines. Like truthfully the genre isn't just Romance based never was and never has been.