The TurboTax article that you found is general in nature, and doesn't discuss the specific rules for New York, New Jersey, and the Covid-19 pandemic.
New York considers your wages to be New York wages. Because of the Covid-19 pandemic, New Jersey will accept New York's position that the wages are New York wages, even though you actually worked in New Jersey. So you should allocate all of the wages from the New York firm to New York, as shown on the W-2.
Since you are a New Jersey resident, you still have to also file a New Jersey resident tax return in addition to your New York nonresident tax return. You will get a credit on your New Jersey return for part or all of the tax that you pay to New York. Prepare your New York nonresident tax return first, then your New Jersey resident tax return.
When you allocate all your wages to New York you should be able to e-file your federal, New York, and New Jersey returns.
