20thwin
As it was already commented by @Cheetosdust in this thread, the official FAQ on the Nothing site explains that:
You can pair your ear (1) to as many devices as you’d like, however only 1 device can be used at once.
You can change which device your ear (1) connects to via your device’s Bluetooth settings.
Your ear (1) will automatically connect to the last device it was paired with when you remove the earphones from the case.
Maybe other Community members that have already some experience using the ear (1) have found another way.
You can also send this directly as feedback to the company, so they can consider implementing the feature in the future. 🙂