It took me several hours of painful reading around to understand what works and what doesn't where the combo of macOS + Docker + X11 forwarding is concerned. So I am writing this down for my own future reference.
tl;dr: Follow the instructions in [this gist][1].
open -a XQuartz && \
xhost +localhost && \
docker run --rm -it --platform=linux/amd64 -e DISPLAY=host.docker.internal:0 gns3/xeyes && \
xhost -localhost