Joplin can sync to several common cloud services, like OneDrive. It can also sync to any provider that supports the WebDAV protocol for reading and writing data. My email provider includes file storage that supports WebDAV. It gives me a WebDAV address that tells Joplin where to put my files, and I set up a key that gives Joplin permission. I use that for Joplin sync instead of getting a separate subscription for a cloud service. https://joplinapp.org/help/apps/sync/