I've been using the free midi to style app (on a PC) with a PRS SX600 for a while and with a bit of tweaking you can get some half decent results. You just have to make sure that the correct voice list for your keyboard is loaded into the app before you start. It supports GENOS 1+2, SX900, 700, 600 and I assume the SX920 and SX720 (I don't have the voice list for these).
In 'Easy' mode things can get a bit 'hit and miss' as the app 'guesses' at the correct parts and settings but if you go into edit mode then you can select which sections of the loaded midi file you want for Intros, mains, fills, ends etc. and also set the volumes for Rhy 1, Rhy 2, Bass, Chords, Pads etc. It also allows you to hear the style through your keyboard (if you have it connected via USB) or through the supplied 'sound font' (if using it on a standalone PC). I couldn't find any support for OTS but Hey, this is a freebie app.
I have created a few styles for Hymns from midi files (I play in a church music group) and they sound OK.
The obvious question is that if you have the complete midi file of a song, why not just mute the midi channels that you want to play on the keys and just play along with the midi file instead of chopping it into 'loops'? Answer, because that's no fun!😂
A user guide is also available to download off the Yamaha website.