This is what the policy literally says "A photo or digital version of an official government issued vaccination card listing the guest's name and dates the last dose was administered"

So if you have taken one shot of a two-shot vaccine, then you can indeed produce "A photo or digital version of an official government issued vaccination card listing the guest's name and dates the last dose was administered".

So to me, the answer would be yes, you can get in with just the first shot.

But it doesn't really matter what the policy says - it matters what the ticket-taker checking your vaccine card THINKS the policy says. Do you want to take a chance on that person not understanding what the policy is?

I'd either email the ticket office and get it in writing that you are good or else come prepared with a test.