linuxdeployqt fails to run in a cross-platform Docker container

[glevner]

I use a Docker container to cross-compile my Qt application for AMD64 machines from my Mac (Apple Silicon). This situation seems to confuse linuxdeployqt.

My Docker image is based on Ubuntu 22.04; I run it using the Docker option --platform linux/amd64.

When I try to run the x86_64 AppImage in my container, I get the following error message:

./linuxdeployqt-continuous-x86_64.AppImage
bash: ./linuxdeployqt-continuous-x86_64.AppImage: cannot execute binary file: Exec format error

So, out of curiosity, I tried running the aarch64 version of linuxdeployqt (which I would not expect to work). It says:

./linuxdeployqt-continuous-aarch64.AppImage -version
Error: No suitable fusermount binary found on the $PATH
fuse: device not found, try 'modprobe fuse' first

Cannot mount AppImage, please check your FUSE setup.
You might still be able to extract the contents of this AppImage
if you run it with the --appimage-extract option.
See https://github.com/AppImage/AppImageKit/wiki/FUSE
for more information
open dir error: No such file or directory

Help?