Yes, you can transfer devices you own to someone else. For this, the new owner must already have a Healy account to register the device under.
The current owner can then initiate the device transfer from his/her shop account. The SN number of the device and the Healy-ID of the new owner must be known to excecute this process.
You can find more information on how to excecute the transfer device here.
Please note that subscriptions that are on the Healy can not be transferred and need to be cancelled before the device transfer can be initiated.