How to dump ALL dconf/gsettings so that I can compare them between two different machines?
Use the dump command of dconf (https://developer.gnome.org/dconf/unstable/dconf-tool.html):
dconf dump /
As always you can use output redirection to save the output to a file for later use:
dconf dump / > dconf-backup.txt
gsettings list-recursively needs a full schema name, it doens't work with partial schema names. So You can't use org.freedesktop.
But you can do this with dconf:
dconf dump /org/freedesktop/
Note the different notation here: dconf doesn't use schemas but directories.