Quick update:

I heard back from the ACPI BIOS kernel developers (see:
https://bugzilla.kernel.org/show_bug.cgi?id=201527) and they seem to imply that
the PCI resource issues showing up in the dmseg log are *not* a problem.  Linux
is simply trying to allocate more resources, and that the failure is OK and it
does get the requisite resources required.

See this comment https://bugzilla.kernel.org/show_bug.cgi?id=201527#c8 from
Mika.

I'm not sure where this leaves us, is it a BIOS / PCI resource issue, or is it
a bug within amdgpu?

I've also been in contact with Dell regarding the possibility that there is a
BIOS bug causing some of these issues.  I'm going to need to conduct some
testing on Windows with eGPUs to see if the problem also exists there.

Thanks!
Rob