1-4 of 4 Answers
Considering that the included charging cord is only 8 inches long, I suspect you cannot use them while listening to them. I went and got a longer cord and my suspicions were correct, they will not turn on when plugged into a charger. Ten minutes on a charger gives you five hours of listening time, so I don't think it is too much of an issue for most people.
Unfortunately the issue still exists on the XM4s. You cannot play audio while the headphones are being charged unless you use them wired with the speaker cable. The moment you plug the USB-C cable to charge the XM4 the unit shuts itself off and all powered functions are immediately disabled. That means no bluetooth, no ANC, no Assistant. This is why after you finish charging, to use them again you'll need to power the XM4 back on.
You can listen while charging if you use the headphones by wire, Bluetooth wireless mode does not work, however .
They cannot be used while being charged. You can however use them with a 3.5mm cable, even if they are dead. These will also fast-charge, meaning you can get about 5 hours of life with a 10 minute charge.