Razer Core X enclosure detected and authorised in the thunderbolt settings.
The eGPU seems to be working -
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Iris Pro Graphics 580 (rev 09)
09:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] (rev ef)
I've applied the udev rules as mentioned here: https://goneri.lebouder.net/2021/02/12/egpu-wayland-and-fedora-33/
cat /etc/udev/rules.d/61-mutter-primary-gpu.rules
ENV{DEVNAME}=="/dev/dri/card1", TAG+="mutter-device-preferred-primary"
I don't have another machine with Windows (and thunderbolt) to check that the graphics card is working, but based on the output above I assume it's ok.
In dmesg there's a lot of repeated errors of this nature:
i915 0000:00:02.0: cannot be used for peer-to-peer DMA as the client and provider (0000:09:00.0) do not share an upstream bridge or whitelisted host bridge
so I wonder if I need to disable the i915 module altogether?
Skull Canyon NUC6i7KYK TB3->AMD Radeon RX 570 inside a Razer Core X enclosure
Linux Fedora 33, Wayland, Gnome 3.38.4
Marking this as solved, although not entirely sure how.
I downloaded PopOS and ran that from a usb stick to see if I had any more luck there, and the monitor worked fine from that. So I figured that it must be because it uses X11 still and fedora is on Wayland. So I logged back into Fedora to test out different X11 options but when I did I found everything was working perfectly.
So not sure what did it, but it's working now and I'm happy!
Skull Canyon NUC6i7KYK TB3->AMD Radeon RX 570 inside a Razer Core X enclosure
Linux Fedora 33, Wayland, Gnome 3.38.4