The taxability of your income by the State of Delaware is determined by the laws of Delaware, not the laws of Pennsylvania.
Delaware taxes non-residents only on Delaware-source income.
Title 30, Section 1124 of Delaware Tax Code defines Delaware-source compensation as follows:
1) Compensation, other than pensions, as an employee in the conduct of the business of an employer, for personal services:
a. Rendered in this State, or
b. Attributable to employment in this State and not required to be performed elsewhere.
https://delcode.delaware.gov/title30/c011/sc03/index.shtml
Thus, if you were required to work outside Delaware, the income from that work would not be Delaware-source income, and therefore would not be taxable by Delaware.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
