all you need to do is expose your face for 15 min or so every day and you’ll get plenty
Not according to this(and other sources):
So, someone like you who has fair skin, burns easily and lives in Pennsylvania would be advised to spend 20-30 minutes in the sun with your arms and legs exposed (not your face) between the hours of 11 a.m. and 3 p.m. two to three times a week from March through May and September through October but only 15-20 minutes in July and August when the sun in strongest. If you remain outdoors longer than the specified time, apply sunscreen. (Don’t even try to get sun time from November through February; in your area, you won’t get enough UV to help, and you’ll probably get pretty cold outside with bare arms and legs.
https://www.drweil.com/vitamins-supplements-herbs/vitamins/how-much-sun-exposure-for-vitamin-d/