Excel and other MOS certifications no longer qualify for the MCT program https://docs.microsoft.com/en-gb/certifications/mct-certification Beginning April 1, 2022, the Microsoft Office Specialist certification is no longer accepted for new MCTs entering the program.
There are no Microsoft Official Curriculum (MOC) courses for Excel so you need to create your own MCT is only required to teach MOC courses So there are no restrictions as who can teach Excel