Developer - SAML Single Sign On testing in Azure Active Directory

Hi Everyone! I'm developing SAML single sign on into an app, and I'd like to be able to test this out with an Azure Active Directory account. However, in order to configure an application for SAML integration into Azure AD, I would need to add a "non-gallery" application, which requires Azure AD Premium. 

Am I missing something? I don't really need Azure AD, I just want to test my app in it, and a) I'd prefer not to make a free trial of premium, and b) I'd like to always have this account so I can test things in the future. 

Additionally, I see that with a free Azure AD account, I can integrate "Gallery" apps for free. However, am I allowed to create a "dev" gallery app? I.e. my Assertion Consumer Service endpoint is just a local endpoint at the moment. Is this possible? I see this article (https://docs.microsoft.com/en-us/azure/active-directory/develop/howto-app-gallery-listing) which gives instructions for listing an application in the Gallery, but it seems that my app needs to be ready for production here. 

Can anyone either point me in the right direction or confirm that I understand the situation properly?

Thank you!

-Ricky