How do I access a transient/temporary mount-point (e.g. ISO file, USB drive) from inside a container?

[CybeatB]

Specifically, I'm trying to follow these instructions (Arch Wiki) to create a Windows recovery drive, because I need it to install a firmware update that's only distributed as an EXE.

I'm on Fedora Kinoite 38, and I don't want to pollute my overlays with a package I'm only going to need occasionally, so I'm trying to run everything inside an Arch container. But I can't mount the ISO from inside a container, and when I try to mount it on the base system, the container can't see it.

cybeatb@arch-container $ sudo mount --mkdir ~/Downloads/winimg.iso /media/winimg
mount: /media/winimg: WARNING: failed to setup loop device for /home/cybeatb/winimg.iso

(I don't actually know what this means, I just assume it means that mount is on the long list of things that don't/can't work inside containers.)

Ideally, I'd like to reconfigure an existing container to handle these kinds of temporary mount-points dynamically, possibly by giving it permanent read-write access to /mnt or /media. It seems like the "recommended" approach would be to bypass distrobox, manually hard-code all of the mount-points into the container config with podman, and remember to delete the container before I unmount anything. It feels like there should be an easier way.