I mean, he doesn't think they're not attractive? If somebody said "hey, I've got a mad crush on that Avalon cutie" Vash would 100% have their back in support.

I love it

Yes! Jinx finds them older-sibling-pretty and Lucifer could be into that, with time

They'd like being called pretty, especially now that they think of their default form as their body instead of just something they threw together

Lucifer...they'd find it less weird that he was into them physically, since they don't know him that well