We do not provide a ready-made image for Raspberry, but packages for Raspbian: https://docs.cozy.io/en/install/debian/
We must however warn you that these packages are not very stable, and that the future of Cozy on Raspberry is not guaranteed. In fact we use the CouchDB 2 database, however its developers have abandoned the ARM platform. We should therefore run CouchDB2 on ARM, but that requires a certain investment and for the time being we don't have the resources to do that.
Cozy's installation on n therefore requires getting one's hands a bit dirty and the long-term sustainability of the solution is not guaranteed.