If your main, primary home, to which you intend to return, is in PA, then your PA is your state of domicile, and ALL your income is taxable by PA, regardless of where you earn it.
Illinois can tax you as a non-resident on your income earned by working inside Illinois.
Therefore, for 2020 you will file both a non-resident IL return (reporting your Illinois income) and your normal resident PA tax return (reporting all your income, including the IL portion). You'll be able to take a credit on your PA return for taxes paid to IL, so you won't be double-taxed.
Chicago does not have a city income tax.