Getting Reaper to automatically route to my Scarlett i1820

So, what I’ve been trying to do is get Reaper DAW working under CachyOS. It took a bit of fiddling with, but I eventually got it going with the help of Grok and qpwgraph.

But how I would like my system to run is something like this: When I open Reaper it uses Jack exclusively (‘pw-jack reaper’) and routes to my Scarlett i1820 USB monitor speakers. All other sound (video, systems sounds, etc.) should route to my Ryzen onboard sound and just use my computer speakers.

Now that’s pretty much what I have. The issue is, I can’t get Reaper to automatically route to my Scarlett. I have to faff about with qpwgraph, disconnect Reaper from my Ryzen onboard sound, connect to my Scarlett i1820 USB interface, and then it works fine.

But I’d like this to happen automatically, and CachyOS has been resisting every attempt I’ve made. I’ve made custom desktop launchers, wireplumber configs, I’ve tried Helvum over qpwgraph… and nothing works. As soon as I restart Reaper, everything reverts back to Reaper using Ryzen onboard sound and I have to go through the whole process again.

Does anyone know if there’s a way to achieve this, or am I just going to have to put up with doing it manually every time?

Have you set in Reaper the proper devices, and are the proper devices (your interface) configured and on when the system starts?

Yes, I have Jack chosen in Reaper and that sticks on reboot. Also, when I turn my Scarlett on, it shows up in the volume widget, is manually switchable, and functions just fine.