Would it be still possible to install Debian, and do the USB workaround on the installed system?
Why on Earth do you need internet just for installing? Is it a netinstall maybe?
Try to install from a Debian live, get one from here:
https://cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/
I guess you don’t have everything installed right.
But I don’t Fedora, have zero experience with it, so I have no idea what exactly you may miss.
Arch has a nice table about what works with DR and what not:
https://wiki.archlinux.org/title/DaVinci_Resolve
This may help you to get some clue.
Edit:
I’m trying to find that video, still no luck…
Only find stories, that Davinci won’t work with mesa-opencl, but those from years ago…
And all of a sudden found this one:
https://nobaraproject.org/docs/davinci-resolve/configuring-davinci-resolve-with-amd-gpus/
Note:
Great news! DaVinci Resolve -finally- works without any AMD proprietary drivers required!
And
some users may need to install the following additional packages for DR to run: mesa-libOpenCL
So I’m positive to make DR 18 to work on an older AMD (such as RX550) using only distro-builtin packages.