I don’t use MIDI inserts much, but it occurred to me that it should be possible to configure one to simulate a strum effect in real time. A few minutes playing around got me to quite a useful setting in Arpache SX. See pic. As you can see, the chord is played straight on the downbeat, but the result is quite a nice even upward spread of notes.
If you switch from PPQ to clicks, you can get the chord to sustain quite naturally. Similarly changing the step size will give different FX as PPQ is tempo related. You can use clicks here too, especially for faster strums
Your original question was in regard to playing chords from an external MIDI keyboard. You’ll find that this set up works both with MIDI data in the project and external MIDI input.
Hope this helps.