What if the gender of the kid doesn't matter?

The woman having a baby can still echo the cowboy's lost family because of the circumstances. Having it be a boy or a girl doesn't necessarily matter to the cowboy. He's still going to think of that echoing pattern where fathers leave and the mother and child are left behind to do what they can. This could be a theme throughout the book that will resonate with readers.

This child might be male, might be female, and they might just not have decided to reveal it or that gender doesn't matter so much to the child yet. (I need to not expound on this. It's a soapbox kinda subject that's difficult because I'm genderfluid and prefer they/them pronouns, and I have enough NB friends and other not cishet people around me that some of these assumptions based specifically on gender or sex are uncomfortable.)

What if the child calls themself Bean, and you're not really meant to know much more about the kid than that in the cowboy's interaction?

I think pregnant women are allowed to call that growing human inside them whatever they please. If Bean feels right, go for it.