Some of the modulation will be compatible (will need attenuation at worst), and certainly audio input/out is good to go. But pitch CV is a non-starter; for instance if you have CV out and hope to control the MS-20 with Arpeggiated sequence, the diff between Volt/Octave and Hz./Volt is an issue.
On the other hand, the 'mini' is Midi equipped so you can certainly control it this way. Sound-wise, certainly complementary; the Korg has a VERY different sound and filter section quite different. Have a look around at some of the good MS-20 videos (non-mini). Marc has a few that go in depth, worth a listen.
I pre-ordered an MS-20 mini and got a rock bottom price (one of those 15% coupons which knocked the price down the $519 or something obscene with free shipping) but forced myself to cancel it because my spending was getting out of control and to be honest, I spent too much time (and money) lusting after the next piece of gear last year and not enough time playing. Going at it different this year!
Moog Voyager Select, Taurus 3, Opus 3; Oberheim Son of 2-voice+2; Sequential ProOne; Juno 106; 48 of MU Modular; Kurzweil 250; Hammond M3; Fender '75 Jazz, G'shop Precision, Tony Franklin Fretless, Hoppus, Roadworn 60's Jazz; Mesa Amps; MF101,104M,105M