I can report above solution of putting this into /etc/rc.local:
# Disable wake computer from mouse movementfor f in /sys/bus/usb/devices/*/power/wakeupdo echo "disabled" > $fdone...also works on KDE Neon (based on Ubuntu 20.04) for disabling wakeing up by the Logitech Unifying Receiver. Thank you very much!
Note: Disabling devices in /proc/acpi/wakeup didn't work for me.