RapidCompser now saves any controllers in the phrases.
You can use other virtual instruments if you don't like Ample but you will need to convert the keyswitches if you are using GP files.
The main thing you can save it all in a phrase that will fit over any chord progression/scale. If you have midi you have made up import it into RC then convert to relative form and save it as a phrase with any controllers.
What are you using now to play GP files RSE or another virtual instrument ?
There is also Notion/Progression that will import GP and work as a ReWire slave in Biab.
If you have issues with RapidComposer go to their open Beta Development forum and type them out and suggest ideas, improvements or features you have as they are usually implemented very quick and you don't have to wait years.
I'm not going to drop 199 € on RapidComposer, so I'll wait for another 40% sale.
FYI, 41 Fingers YT channel has a bunch of excellent RapidComposer videos. He's also posted some with it paired up with Scaler. Recommended.
41 Fingers YouTube channel