New cosmetic changes inside:
I talked with owners of PiNEBERRY and my HatDrive! for M.2 disk will by soon. In this case I removed Pi and have place for drive.
Because I had Pi5 on desk I done mod.
If you can’t find mod 
… it is new pins for power switch near HDMI port. I soldered standard pins like in GPIO because it is not enough pleace for biger socket/plug that I normally use.
Clean soldering without problem 
On pins I mounted plugs from desktop MB.
Everything works like should. One touch in Volumio system off, second touch system on. On Raspi push button gives menu and you can use power off or reboot.
I probably will install microswitch on front bottom or on rear panel because want have clean front panel like now.
EDIT:
Rest of mods inside to better performance:
- I shortened USB cable to XMOS. I use ViaBlue K2 silver 1 meter. Now I cut it to about 25 cm for better signal.
- I changed power cable. First was longer and thiner. My power supply can gives continuously 5A and more if need in peek. I changed cable because when I conected M.2 drive via usb 3.0 and started play local music my Waveshare was black on 1 second and Xmos was disconnected. When I changed wires from 0.5 to 1mm and almost half shorter I can play from M.2