The difference with Product Manager vs. Project Manager I think is really a Product Manager will have to acquire or start with in-depth knowledge about the market a product operates in. In some ways a product manager might be a superset of skills including project management. There could be organizations big enough where these are different roles though. If you have knowledge/experience and interest in some domain, start there since that is helpful.
There are project mgmt classes and certifications like PMP or Scum Master. I don't think highly of orgs that require certifications on things like this, they tend to focus a little too much on strictly following a certain framework's guidelines as rules. They could be a way to get a job and some experience under your belt. I think the PMP cert is shorter if you have a college degree and it does require doing PM work as part of the cert, has different levels, etc.