I really wanted one, but it wasn't available at first on the domestic Bellion
I'm not sure if it's available now...
Meanwhile, on AliExpress I found a 3D printed Garmin mount that fits my handlebar (canwin)
but the 850 option wasn't available
I contacted the seller asking if they might be able to make it
They said they could make it if I just waited, so I purchased it
(the 850 that wasn't in the purchase options ended up appearing)
I waited about a month to receive the shipment
The result is excellent—the integration feels perfect
I'm using it with the Fly12 front light and it attaches securely without any wobble