Isn't wfgui free to use, in which case you already have what wfgui offers. I thought that what you wanted was to combine it's functionality with some PicoScope features into a single tool which, as I mentioned before, is what the SDK can be made to do (this sort of tool, i.e. wfgui, would not be the right fit for Picocope 6). That's why I was asking you to start a discussion on what sort of PicoScope functions you would like to see integrated.
Regarding measuring voltage in dBu (remember there is no dBv anymore - my understanding is that for rms Volts ref to 1mW into 600Ω the standardized unit name dBu replaced dBv to avoid confusion with the standardized unit name dBV for rms Volts ref to 1V) you can already do that with Math Channels in PicoScope 6. You just create a channel with the value '20*log(sqrt(average((A^2)))/0.7746)'. Similarly, specifying the voltage in RMS instead of p-p is just a scaling/conversion factor of 0.707 x the Amplitude specified in the Sig Gen.