How to list all files on the system
My best solution is the following (for bash shell)

shopt -s dotglob
for f in /* 
  sudo gfind "$f" -path /System/Volumes/Data -prune -o -print 2&gt;/dev/null
done
shopt -u dotglob


where, in place of -print, one can use several other commands.

The most part of files in /System/Volumes/Data are the same as in /, with few and not much interesting additions.

Moreover, the more compact solution gfind /* does not work well, because produces many loops that prevent the listing of many parts of the full listing.