Rename is a fairly common feature on Bluetooth speakers and headphones, for example my Bose NC-700.
My phone will show me a different name for a "renamed on phone" Bluetooth device, but all other devices in the area won't.
Otherwise, I trust many folks in an HN comment section would reminisce on stories from their earlier years, where they'd rename the Bluetooth devices around a densely-populated area to cause mischief.