I’d cater a gay wedding wearing a bowling shirt, shorts and sandals.
Don't do it. They might insist that you cater their "wedding" naked, wearing nothing but a black bow tie & a pair of socks, possibly.
I was at a wedding in January where the guy videotaping the ceremony was wearing a teeshirt and bluejeans. Apparently you would fit right in these days. Regardless of the sexual orientation of the happy couple.
My understanding is Gladiator attire is preferred.
If you’re catering a wedding that is having pizza at the reception, sartorially, you would probably fit right in!