Is it possible for a cozy app to support signups from other users? For example can I build and deploy to cozy? i.e Cozy as a development platform.
Cozy is a personal server, mono-user. So applications inside Cozy are only available to the owner of the server.
Here is the documentation explaining how to build applications for Cozy. If you need more informations, feel free to ask.
To complete Clochix’s answer, you can develop your application and make it available to other users through the Cozy Store app (based on our registry). Like that, other users will be able to install it if they want and use it.
To publish an application in our Store, it’s not yet fully automatized, but we can help you during the process.
More details in /apps - Apps registry - Cozy Developer Documentation