This documentation is for bazzite, but they have a lot of the same stack under the hood. “Broadcom’s WL driver can be installed since it is needed by some hardware. Disabled by default. Enter “just use-broadcom-wl” to use it.”. You could try to see if aurura has the same “just” options, that’s where I would first research. If not, then yeah, “rpm-ostree” would be how you install the package, just like you said, just not sure of the commands for local files. Also there is a tool to “roll your own” distro built on top of any of the ublue work, it’s basically how bazzite and aurora exist. So you can layer the packages like the other option you said. https://github.com/ublue-os/image-template
What GPU are you using? What influenced you to add “Oibaf PPA” instead of using the default built in Mesa drivers that came with Mint? No judgement, just trying to figure out what led you here, so we can unravel it. Because as the other poster mentioned, Vulkan for Amd should have worked out of the box on a fresh install.
Edit, to clarify, did you add the repo because you thought that mint didn’t have drivers and that was the way to get them? Or was there a different reason you needed to add the repo?