I just followed their instructions and on 2 of the nodes in my cluster, I migrated all VMs/LXCs off and then did the upgrade and they went through without a hitch. For the last one, I just YOLO'd it and powered off the VMs/LXCs and upgraded it and it also went through without a hitch.

One thing I did find interesting was the systemd-boot packages needed to be removed and were on 2/3 of the machines. I basically intentionally keep their config as close to identical as possible, so I have no clue why it was only needed on 2 of them.