Typically you can find insurance companies that will insure you with only a learner's permit. The insurance company may require you to take out your auto insurance policy with an additional fully licensed driver. And depending on your age the insurance company may request that you obtain a regular driver's license within a certain period of time, usually 30 days.
Pennsylvania (PA) law does not dictate a minimum age for owning or registering a vehicle so you should be able to buy one and register it with no problem even if you are under 18.
You can get a quote for Pennsylvania auto insurance here.