Recently, I was trying to search for a good frontend certification. Note: I mean certification, not course; certifications similar to ones the Linux Foundation and the OpenJS foundation provide respectively.
It took a while before I landed on a couple of certifications by freeCodeCamp and another to be released, by OpenEDG which seemed to be along the lines of what I had in mind.
Considering how Mozilla is such a well-established name in the community, certifications from the Mozilla Foundation would also be widely recognised. Mozilla already provides great documentation for web developers in the form of MDN. Having certifications for frontend and backend devs (not limited to just these but you get the point), would also be a monetary opportunity.
I think this will attract a lot of new and existing web devs to test and prove their skills while also spreading Mozilla's reach and maybe even making some money on the side.