This looks like the same issue, thanks for sharing.
I did run git submodule update --init somewhere at the start (from the host). I had forgotten that after several hours of debugging!
Are you using Windows or Linux as host OS?
I’m running a basic Ubuntu 22.04 install under WSL. There could be additional issues coming from WSL but I doubt it, I run other dev containers on this setup all the time, and I’ve never made any changes to the default user/groups.
I did see that when I had the data/ folder at 777 so that I could progress past the initial setup screen, Nextcloud created some files inside with owner/group 1001 (as viewed from outside the container). This user/group doesn’t exist on the host. Docker is 999 which is the highest number assigned.
Inside the container, 1001 belongs to an entity called devcontainer:
getent passwd 1001
devcontainer:x:1001:1001::/home/devcontainer:/bin/bash