Unless this is a requirement of your specific council OR your charter organization the answer is no, vendors or guest speakers do not need to be registered or YPT trained.
Here is a cut and paste from the current YPT FAQ on scouting.org:
♦ Q: Do the September 1, 2023, changes mean that third party vendors must be registered with the BSA?
A. No. Youth Protection and supervision remains the responsibility of the unit and Scout leaders. Vendors and other third parties must be licensed businesses that carry proper liability insurance, units should be sure that they use reputable