Keyboard (KB) usually won't wake up iMac; makes popping sound; in Bluetooth; no keyboard found.
Using Apple wireless KB which seems to work except in waking up; it may work if the "sleeping" has been for a short period but this is conjecture as I've noticed the KB does seem to function if I have initiated "sleep" via the menu and then used a key stroke shortly after. "Diagnostics" also doesn't seem to function on this (MontereyOS) device which may be related.