It definitely isn’t Open Source. They are using a modified version of the AGPL that prevents sale. This is a terrible idea in my opinion. In part because it makes it incompatible with all existing AGPL code and also because it is super confusing to use the familiar AGPL name for something that isn’t open source. I don’t know if the FSF actually allows this. Wouldn’t the license text itself by subject to copyright with derivatives being disallowed? Not sure. Unfortunately AGPL is not trademarked and I’m not sure it could be given that no products are being sold but that’s how Linux protects itself from things that are not Linux being called Linux.
I was so excited about this project too since I’d heard it was open source but I’m definitely not interested in supporting the proliferation of non open source licenses, especially not ones that make themselves look like open source licenses.