Note from practice 2021-03-05:
Working on palmar flexion as priority piece. Slow rehearsals of transition move and Covid-19 day-4 drill all seem to look fine, with clubface aligned to my spine at A6 (slightly toe down). When I move to full speed, and look at swings on film with Mirrorvision, the face is vertical. This leads to a flip/shove to close the face at impact, or I can hold off the flip (if I think about it hard enough before the swing), and leave the face a bit open and hit what I assume would be a push/cut.
I had a mini-realization watching the videos and doing some rehearsals. When I rehearse the palmar flexion move, my forearms arms don't have nearly as much tension as when I am making a full speed swing, and my wrists move freely. I did some rehearsals simulating the tension in my forearms that I feel with full speed swing and tried to palmar flex my wrist and I could barely do it. I did some more rehearsals/Covid-19 day-4 drills, and then hit some balls with full swings with the conscious thought of less forearm tension, and suddenly I could feel the palmar flexion move. It was too dark to get any video, but I'm going to record tomorrow and see if the clubface looks any different at A6 compared to video from today.
Day 12. I had two five-minute practice sessions during work breaks today. I was mostly checking that I could swing and hit a ball, given my arm (vaccine in arm yesterday). Success! Off a mat, into a net, real balls, 6- and 8-irons.