That's all a matter of instrument-design, which we offer in an extensive way (modular).
In any case, surely we support midi-out as well, so you could control any third-party synth in the background. Tho I'm sure that our instrument-editor is flexible enough to cover all those. Unless that guitar-thing from FL does physical modelling, it's just a sample-player. Strumming is a matter of triggering the right samples/notes at the right moment. All that is a matter of instrument-design.
In any case, surely we support midi-out as well, so you could control any third-party synth in the background. Tho I'm sure that our instrument-editor is flexible enough to cover all those. Unless that guitar-thing from FL does physical modelling, it's just a sample-player. Strumming is a matter of triggering the right samples/notes at the right moment. All that is a matter of instrument-design.