He got off on a technicality. Even many of those that voted not to convict said that they thought he was guilty. They just didn't think they could convict a non-sitting president.

False cures for diseases, yes, people absolutely go to jail or receive massive fines. Sometimes on charges of fraud, sometimes on charges of endangerment. If your fake cure doesn't actually do harm (and is just useless) then you can usually get away with it. A quick google search will show you multiple stories about criminal charges for fake covid cures.