I had some good success with guessing the Artemis II crew, knowing that Reid Wiseman had just stepped down as head of astronaut office, Canada was sending an astronaut and the wish to not have the crew going around the moon be all white dudes, that left a small number of highly qualified options.
Artemis III is to LEO, it's a different vibe. I see ESA is streaming the event, so that's a clue an ESA astronaut might be involved.
ESA previous said that a german astronaut would be the first to fly to the moon but with this being LEO, and a mission involving testing hardware the ESA jet pilots have an edge so I'd guess Luca Parmitano or Samantha Christoforetti.
From NASA, Andre Douglas was a backup for Artemis II and seems like an obvious choice.
Raja Chari has been working on astronaut development for HLS since his flight in 2022, he seems like someone already well positioned for this flight.
Jasmin Moghbeli has also been involved in HLS, not as much as Raja though.
Nicole Mann also has a lot of relevant experience, working with exploration systems development.
There's definintly some other great choices, Woody Hoburg was on the Orion heat shield review team and Artemis III has another new heat shield.
And I won't be surprised if there's choices not on this list.