I think Lokad's supply chain lectures are an excellent source. They are all available on YouTube.
MIT offers a MicroMasters in Supply Chain Management through the edX platform. I haven't taken any of those courses, but maybe you can find something interesting in the syllabus. They are free and you can have the option of earning a certificate for a small fee if you complete all the requierements. This program can be half of the on-campus Supply Chain Management master's program.
Maybe someone that has taken this program can comment and tell us if it is worth it?