What mecha story has gay shit? I’d like to watch it.

The most popular recent one is Brave Bang Bravern.

Keep in mind Japan has heavy censorship so a lot of the “gay mechas” are implied and subversive theming instead of openly gay.

Squid in a schoolgirls ass is just fine and dandy but heaven forbid someone is gay.
Censorship rules always end up stupid because individual morality isn’t consistent and blacklists are never comprehensive