Well, I appreciate the reminder that I can’t trust KDE Discover to list packages in the Fedora repos 😂 sadly necessary in this case!

Updated my initial post but I ran rpm-ostree install plasma-bigscreen and it worked! Will be keeping an eye on things next few times I update to see if it causes any issues.

Fair, I was just going off of the official Bazzite docs which specifically say “not recommended, use as a last resort” and “Layering packages irresponsibly can be destructive and may prevent updates as well as other issues until the layered packages are removed.”