MAC addresses can sometimes be used to identify the maker and potentially model of the device even without the device in hand. This is called the OUI (organizationally unique identifier). Please see https://en.wikipedia.org/wiki/Organizationally_unique_identifier .

There are several lookup tools on the web , such as https://dnschecker.org/mac-lookup.php or https://www.wireshark.org/tools/oui-lookup.html . Dell has a range of MAC addresses that it uses, and Apple has another. MAC addresses are generally unique to a device, but some manufacturers re-use MAC addresses within a particular model or part number. Some devices allow you to change the MAC address advertised in software, for instance Ethernet adapters or wifi adapters. This is useful for connecting to other devices which are supposed to be locked to specific other devices (cable modems). This can be confusing.

The unique MAC address helps you a little in identifying which device is which. However, to be absolutely certain, you'll need to pair it and use it.

Some devices have their MAC addresses printed out on their shell, on a sticker, or under their battery. Some don't, or it has rubbed off with use.

If the mystery device is in range but outside your reach (possibly at your neighbor's), then there's nothing to do. Just ignore it. Some phones or laptops let you turn down the power on your Bluetooth gain and transmit, but it's more of a hassle than it's worth.