What I need is this software altered in a couple of ways:
1) I'd like a simply web interface for a user to enter their home WiFi network's name and password. Once input, a list of speakers should be output. The user can then select a single speaker from this list.
2) Once selected above two physical knobs will be attached to a Arduino UNO board. One will control volume of selected speaker and the other will do control volume of all Sonos speaker units currently grouped with the selected speaker (not all speakers on network).
3) There is no support for Wifi built into the project link above - you would need to find a suitable WiFi support library to do the WiFi connection step you described that is compatible with the Arduino Uno.
I can provide an Arduino unit and/or volume potentiometers (volume knobs) if required. Would need them returned to me at conclusion of project.
A bit more detail on the project. Overall, I'm building a case that a Sonos Play 5 sits in. No LCD display. Some people like the sound of a Sonos speaker, but want a different design. The case that the Sonos speaker sits allows the user to use 2 knobs that are on the front of the case. These are connected to an Arduino Uno board which then controls the speaker.
User flow should be:
1) Plug in USB cable from Arduino board to computer (if possible to do this setup without USB cable and instead via web-connected smartphone, that would be ideal.
2) Download software (this project) from Internet
3) Use software to specify Wifi and enter a password
4) Software should present user with a list of Sonos speaker names (these are named by the user when they add units to their Sonos system).
5) User can disconnects their computer and can use the speaker via their phone or web app as normal. They can additionally use the knobs on the front of the case to control the speaker volume.