app4g

tried https://github.com/whomwah/qlstephen/issues/112#issuecomment-882400674 but doesn't work.

> 1. In a single .fit file with a custom developer field for the second power source This is a good idea. But it will depend on the WEbSite if...

How about webTrainer?

poursuivant per the TdF of Tete De La Course and poursuivant

I found a possible solution for you. 

did you take a look a this mathematical model from this site? You use Power to convert it down to Speed utilising the variables of slope / Air resistance and...

I briefly scanned thru the 2 links you provided, haven't read it in-depth. There's also discussion about this by some of the Golden Cheetah developers (https://github.com/WouterJD/FortiusANT/issues/175)

> In this case, I think APP send resistance command to trainer, rather than target power. Is that correct? The app can send 1) target power (using a fixed or...

if you're connecting via bluetooth, I don't think this is possible. Or are you on ANT+?

https://groups.google.com/g/golden-cheetah-users/c/vpUq4jn587Q/m/6sHmDPEKAgAJ some discussion there.