NJ and PA have a reciprocal tax agreement. That means that compensation paid to NJ residents by a PA employer is not subject to PA income tax.
Thus, if your entire income from PA consists of employee compensation, it is not necessary for you to file a PA nonresident income tax return.
https://www.state.nj.us/treasury/taxation/njit25.shtml
As a resident of NJ, ALL your income is subject to NJ taxation, regardless of where you earned it. Therefore you must file an NJ resident return. Note: You are entitled to a credit on your NJ return for the Philadelphia City wage tax you paid. To obtain the credit, file Schedule NJ-COJ with your NJ return.
https://www.state.nj.us/treasury/taxation/njit14.shtml#:~:text=The%20New%20Jersey%2FPennsylvania%20Reciprocal,the%20taxes%20paid%20to%20Philadelphia.