Build script compat with shields

[JJ-Atkinson]

First off, if this isn't a goal of the project, please let me know and just close the issue :).

So, after some effort I got podman installed and figured out how the buildscript is intended to be used. I'm attempting to use the cradio layout (34k split) with nice_nano_v2. Since shields aren't supported in the local build script, I'm having to resort to using the gh actions script (not terrible, but quite annoying :) ). I tried to make a bash script with yq that used shields as well, but I'm no bash wizard, so I'll spare you the pain of the non-working code haha.

[urob]

This would indeed be nice extension. I hadn't needed it so far to look into it. Using a lightweight processor like yq would be my preferred route as well.