x2apic=false in the Xen command line got me a stable system. Was able to plug a usb wireless adapter in via a USB-C port on the back to apply updates.
Latest kernel resulted in a working and stable AX210 wifi adapter.
Suspend/resume are still not working but I can debug that later.
Only weird issue left is the external USB type A ports do not work at all. Nothing in dmesg in sys-usb or dom0 on any device insertion.