It's striking how similar is the sound of the PPG Wave to the Poly Evolver Keyboard. It makes me wonder if the PEK's blue panel was meant to suggest this and place it in the same family of instruments, together with the Prophet VS.
I think this video rather demonstrates an approximation of particularly harsher PPG sounds, but they still differ from the actual PPG sound (which in itself differs depending on what revision you use) - I'd say they're far too busy by comparison (I'd call that the typical over-compensation effect in emulative sound design):
(2.2)
(2.3)
I always thought of the PPG and the VS as complementary hybrid synths both in terms of sound and features.
The Evolver is somewhat closer to the VS due to the same digital waveforms being used and the four oscillators as opposed to the two oscillators and wavetables that have been utilized in the PPG. And there's of course the connection to the Wavestation too, as the Evolver allows you to program wave sequences (although in a very different manner than on the Wavestation). In contrast, the Evolver must have a hard time approximating anything PPG-like as a non-wavetable synth.
In the end I think they all sound vastly different due to utilizing very different ingredients and also different sounding filters. The PPG Wave has that early digital grittiness in comparison to which the Prophet VS almost sounds polished while the Evolver could sonically stem from the 1980s New Wave or the 1990s Industrial era, which gives it that sort of overarching hybrid sound character.