Sebastian I found a really interesting solution on stackoverflow
In terminal:
sudo xhost +
sudo -i -u username
command you want to run
sudo xhost -
Like this I can run gnote, rednotebook, whatever program in the budgie session with the budgie user as the GNOME user accessing the GNOME users data. Even playing music with rhythmbox accessing the GNOME's user music library.
Downside: no MPRIS media info in Raven.
Will handle playing music maybe differently. But for everything else this seems to work extremely good.
Will play around with this solution. Will try to edit the desktop files for gnote etc that they run a script with the above commands.
But I am still open for alternatives.