Paolo of Synthmania also has very good advice on playing not just guitar but other instruments on keyboard. Basically it all amounts to considering and imitating the range, note spacing/reach, and techniques used on each instrument. E.g. articulating/arpeggiating chords slightly to imitate a strum on instruments like guitar or harp, using much wider spacing of notes within chords than piano to imitate the tuning of guitar strings, etc. There are always limits but small changes make a big difference in how realistic it sounds. Same of course goes in reverse when using a guitar as a synth to play keyboard sounds.
https://www.youtube.com/watch?v=bmQETKtz1WsYou can find timestamp links for various instruments in the description:
Acoustic guitar - 0:44
Banjo - 6:39
Orchestral Strings - 9:45
Choir - 13:06
Flute - 15:17
Saxophone - 17:32
Trumpet - 20:14
Harp - 22:33
Marimba - 25:20
Electric Bass - 26:49