I have developed an extension to use the Fosi Audio VOL20 Bluetooth Knob as a volume control for any Roon Zone.
You will have to build it yourself with a Raspberry Pi and some instructions.
No support is provided. You can use your favourite AI assistant to help you with any problems.
You will need to be familiar with the Raspberry Pi platform, and know how to do basic bash-type things on the Raspberry Pi.
No disk image is available.
Very nice of you to offer this.
Maybe you should think about offering it in Extension Manager through @Jan_Koudijs.
He has a lot of user’s of his software and this could be a good addition
Since you need to add certain information related to the Bluetooth device, it will need another round of coding before it can be included in the Extension Manager. So for the time being it’s DIY.
Good luck with this, I am sure it would be a popular extension