aarch64 Flatpak cannot display on Chromebook (Debian 12)

[nickgirga]

I'm using a Lenovo Duet Chromebook (aarch64-based). It runs ChromeOS, but features a "Developer Mode" that allows you to install a Debian 12 (bookworm) container and run Linux apps. I've used several other Flatpaks that work just fine. However, SASM can't launch properly with this setup. Every time I try, it spits out this error:

qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, xcb.

I tried granting practically every permission using Flatseal, hoping that SASM could make use of a system library or something, but that didn't help.