I bought a battery-operated PIR alarm with a keypad to arm and disarm. It can wake the dead! It's located at the far back wall, so would be hard to get at if a thief didn't know where it was. I specifically went for a model that didn't have telltale LEDs.
It's still available for sale
https://www.ebay.co.uk/itm/333597076...IAAOSw4YJZZNfJ
My bro went for this remote control type.
https://www.ebay.co.uk/itm/114411344...3ABFBMqr-MopNg