Sure, but a cis man could also be dating a trans woman in any of these scenarios, and no one would say “heterosexuality” was what was preventing him from becoming a dad.
When people joke about lesbianism = no pregnancy, it’s because they’re assuming all lesbian relationships are between the same kinds of bodies having the same kind of sex.
I’m a lesbian, I’m not changing my label to pan because I’ve dated trans women. Most people who feel attraction feel it before even learning what genitals the other person was born with.