Virtual power is interesting… I used to use it for years before I got my power meter.
I was thinking of creating a device to turn speed and cadence sensor data into an ANT+ or bluetooth power meter signal - this would mean you could use it with anything… I think it’d be relatively low cost to make and could be adjustable - eg you could calibrate it against real power to get an accurate reading or just adjust it manually.
I wonder if there’s any demand for such a thing… Off the turbo trainer it’d be useless due to too many variables, but on the trainer it’d be pretty accurate I think… the only variables there (after calibration) would be heat really (as the trainer and tyre warm up their efficency will change…) but you could actually compensate for that too…