This issues has had me sticking with the old BTT images for ages, then I found a different issue with those so was forced to come back to try again with Armbian. After going down many rabbit holes a friend said just install KlipperScreen earlier than you normally would when running up a Klipper install, that will pull in network manager. It was so simple for my use case I hadn't even considered it. Worked a treat, I could set up the wifi on the touchscreen and it survived reboots.
I then found a slow down in the boot process because networkd was still waiting for a connection, a solution to that wasn't as hard to find I ran these two commands in the terminal and now it doesn't slow anything down during boot up. I have no idea if this is the correct way but I'll post it in case it helps anyone else following the same breadcrumbs I've been chasing.
sudo systemctl disable systemd-networkd-wait-online.service
sudo systemctl mask systemd-networkd-wait-online.service
