Yep it's overwhelming.
Sounds like you are trying to use Multibeast to create the stick? There are certainly a lot of options. There is contextual help, and there should be guides for z3xx series boards. The good news is a lot of Multibeast is optimization, and you don't care about that, you're just trying to get it to boot. Sound, ethernet you don't need to worry about immediately, and USB should be good with USBInjectAll (whatever option that is in Multibeast). I would use system definition iMac14,2, it's the most broadly compatible. For graphics, I THINK your RX is natively supported with enabling ATI (ATI==AMD I think). If graphics gives you headaches you can always disable discrete and use the IGPU in the BIOS. The main kext you must have is FakeSMC.kext.
To be honest, once you build the stick with multibeast I think I would immediately download the latest clover and run it on top of the stick so you have the latest and greatest. In clover, you want to make sure you have the apfsdriverloader.kext that pulls apfs.efi off your boot partition.
Once you get your system booted then you can try to start moving the custom stuff in the config.plist on the NVME to the config.plist on the stick. You want to go slowly so as to not corrupt the stick. clover supports using a specific config, defaulting to config.plist, so you can create config.1.plist with a few changes, and manually select that at boot up, and if it blows up, just reboot with your known good config.plist. Your nvme allegedly has a well configured config.plist and set of kexts (and maybe some acpi/patched amls). it's possible that you'll figure something out and you can just start booting off the NVME. Good luck!