This video, via Frederic Gerchambeau, demos using the Korg Volca Keys as a three-voice synthesizer.
The Volca Keys lets you play up to three notes at a time, but uses the old-school paraphonic approach, where the three oscillators can be independently controlled, but they are fed through common VCA, with a single envelope.
The Volca Keys architecture is three VCO’s, with 1 VCF, 1 VCA, 1 LFO and 1 Envelope Generator. This isn’t as flexible as having an independent VCF/VCA/LFO/EG per voice, because each note retriggers any held notes. But, as the video demonstrates, the Volca Keys can still deliver powerful analog sound.
The demo was created using a a Korg Volca Keys and a Make Noise Echophon.