There's OpenRepos (be sure to filter by 'sailfish_app' which has third party applications and extra packages (no quality control). The Jolla store (which has applications for Sailfish OS and Android) has no website (and actually no quality control either). Most people upload their applications to OpenRepos, because the Jolla store is extremely strict in the libraries they allow applications to access, making it impossible for many run of the mill applications to be available through officially supported channels.