Reagan was a union leader and became a spokesperson for GE before becoming governor of California though, that’s how he honed his public speaking. Trump was a well-known businessman and TV personality (note I don’t say successful 😂) so I think some deluded people thought he’d be competent in office.
Meghan would really need to raise her public profile here and probably ditch the Duchess of Sussex title too, which she doesn’t seem keen to do. Harry wouldn’t be a bad First Man though, he’d be familiar with all the protocols.