it would make a good combination that would work with most digicams that have a remote
shutter.
Just buy one of these very cheap "USB Control Relay Module serial port" in the internet. a relay is over killing for the job but because these modules are so cheap (~5€) that does not matter. And it is so simple that even somewone with two left hands can make it.
Then connect board to the remote shutter. Now a indi driver can control the remote shutter and get the resulting image over the eyefi system.
I think it best to create two indi drivers
One other point, the exif data becomes very imporant in this driver the get the really used settings of the camera.