That's still kind of a reach, if you're asking me.
Also we're all kinda looking at this with a very black and white viewpoint (insert joke about how of course we are, only the first page is colored)
This stuff is never actually all that clear cut irl either. We are in fact looking at the very start of these two's journey together, and likely not going to see more beyond this.
Does the character have an explicit identity as a trans woman? Well, you're right, we can't definitively say that for sure. Does she know it's an option? Well. We can't say for sure. We could take the interpretation that homare has a fluid, or perhaps under-contemplated gender identity.
Is kuramichi using masculine pronouns in that panel? According to you, yes. But what does that really mean? What actual interpretation can be drawn from that? Is a high school gyaru going to be Wokezilla 3000? Well, maybe. Maybe not.
The story is just that- a story. What one takes away from it is going to be inflected by the lens you bring to it.
But saying all that.
"I used to wear my sister's clothes because I liked it and I still want to dress femininely now, despite social norms and Some Guy yelling at me that I'm a gross weirdo for that" is not a cisgender thing to say.