I don't know if this is related, just reporting my experiences.

Everything from eokpkg check is ok.

uname -r says 5.10.5-167.current and I'm using Budgie.

Yeah that's the same place I pulled the command from. Sorry about not including it originally, it would have helped.

I've dug around in both the package.yml and QEMU 5.0.1's source code and I don't see where that distinctive seavgabios path is being hard coded or set in a variable.

Yeah I played around with building Haskell a little but it's not a stack I'm super familiar with. Last time I used it was actually to modify a support program to integrate Shellcheck with CodeClimate.

I can build the shellcheck package itself and contribute it, but if the Haskell stack needs updating... is there a bug for what all needs doing?

It's pretty common for languages to self-host. It's really convenient for the language developers but it can be pretty annoying for everyone else if there's no provided bootstrap or when trying to build for a new target triple.