Thanks a lot !
I'm surprised about Saitek/Dragonrise - Win/Ubuntu compatibility : usually I'm able to use both gamepads on both OS.
It was pretty surprising, but that's what the external library we used to assist with controller support says: https://guavaman.com/projects/rewired/docs/SupportedControllers.html (In the chart near the bottom that says "SDL2 Gamepad Support"). It might be that other games are using more robust libraries for controller support.
For now we are still looking into it, and we'll let you know if we find something out. Sorry again those controllers didn't work with the game right off the bat.