Can an Exchange DAG (2010 or higher) run on two different virtual platforms?
Yes, it would be supported. Any supported virtualization product on this list is supported: https://www.windowsservercatalog.com/svvp.aspx
From an Exchange perspective, it wouldn’t care what it rides on. You can mix and match all day long, as long as the Exchange versions are consistent. In fact, the Exchange role requirements calculator doesn’t even care about virtualization, the requirements are the same.
I ran into an Exchange 2010 customer years ago, had a dozen machines in the DAG, everything from 1U, 2U, 3U, 4U servers, from many different vendors and configurations. I was like, what? He said, when a 7 year old machine comes off warranty and another department gets rid of it, he throws it into the DAG. He had like 5 or 6 copies of every database, randomly across all servers. Odd? Yes. Worked? Yes. Supported? Yes. A mess to manage? Yes. Carry that logic a bit further, and virtual mixing and matching would be the same.
I know customers with 1 datacenter on premises (physical/virtual) mix, and the other datacenter in Azure. All works. In fact, as I type that, if you can mix and match physical and virtual machines day in and day out, no reason not to mix match virtual to virtual hosted machines.
Is it listed anywhere? No, not from Microsoft. It’d be a ‘read between the lines’ kind of thing. If A = B and B = C, then A = C kind of leap of faith, but still fully supported.