This webinar is a great resource for organizations no matter what CMMC level you expect to need.
It is released by Carnegie Mellon University’s Software Engineering Institute. This is the organization that helped the DoD develop the original CMMC model. Their recommendations are very authoritative.
Here are the resources that SEI recommends:
DIB Cybersecurity program: https://dibnet.dod.mil
CISA Resources: https://www.us-cert.gov/resources
CMMC Accreditation Body: https://cmmcab.org
CMMC v1.02 Appendices: https://www.acq.osd.mil/cmmc/docs/CMMC_Appendices_V1.02_20200318.pdf