over the past weeks I did some search for SF2, SFZ and GIG Soundfonts for the Zynthian. Below you will find a download link for the collection. Folder structure (If it is too many folders deep the Soundfonds will not be recognized) and some sf2 files are optimized for the Zynthian to be readable.
Initially my intention was putting it on Github but about 11GB is too much for Github.
Please visit the links below and show the people behind the Soundfonts some love for their great work!
http://klemxxiii.free.fr/ https://nobudgetorchestra.net/download/ https://archive.org/details/LesserdevilSoundfonts https://sites.google.com/site/soundfonts4u/ http://beats.codenamehippie.com/ https://github.com/sgossner/VSCO-2-CE/tree/SFZ http://x42-plugins.com/x42/x42-avldrums https://archive.org/details/Soundfonts