Well, I was cautiously optimistic. I removed the .deb version and installed the flatpak version. I was able to launch it and sign in. I was about to try installing a game when I remembered I hadn’t turned on Proton and all that mess, which requires steam to restart. Now instead of just flashing at me I get the Steam “waiting for network” screen, then the icon appears in the task bar (idk if that’s what it’s called in Linux, but in Pop, this is the top right corner where volume, network, etc is). But the favorited icon in the dock doesn’t show the little dot under it like normal open apps would show. If I click on the task bar item, I get the menu, but it’s all unresponsive other than Exit.
I forgot to mention in my original post but this issue persisted through a reimage of the boot drive. That’s not why I reimaged, but pretty alarming that it would stick around through a full reinstall of the OS.