@kate.mason I just ran through this with PB 24, EC 1.11, Qubes 4.1.x:
For the DKMS module, you should be able to skip the sudo make prepare. Wisdom online says that this is not needed for building external modules, and it won’t work without full kernel sources. The module built and installed successfully for me after that.
Shutdown and suspend are working for me, could you try booting a PureOS live USB and see if you can suspend / shut down there? That should indicate whether we need to look deeper in the OS or firmware.
I get the same error from dracut also about /sys/power/resume - sounds like this file in /sys is used to resume from hibernate. Qubes doesn’t support hibernate, so this is probably normal.