Fellas!
Is it gay to like boys? I mean think about it; you're literally a man who wants to kiss other men!
This thread reminds me of a video essay I watched recently, which explored the somewhat related question of whether straight men can be attracted to trans women.
And the answer in both cases is yes, sometimes.
Some (but not all) gay men are attracted to femboys in a gay way and some (but not all) straight men are attracted to femboys in a straight way. And for some men their attraction to femboys is the whole reason why they identify as gay/bi/pan/etc. in the first place. It all depends on how the person in question conceptualizes "being gay".
So to a hypothetical man who likes femboys only insofar as they're woman-coded, I'd say that he can still call himself straight if he wants to, but also the bisexual umbrella is big and we have cookies :3
There's gynophilia, but that can also mean attraction to women. I agree though that attraction to female-presenting people of all genders is a relevant concept here.