The fireworks are returning to Jersey City this year, too. They will be over the Hudson by the famous Grucci family who does some of the most spectacular fireworks.
https://jerseycitynj.gov/news/jerseycitysjuly4thfireworkswillreturnfor2021
As for your question, I don't know. I've never left the city on the 4th. We can see the Hudson River fireworks from my apartment window.
MY pic from my window below. ⬇
(The fireworks look low because I'm in a high-rise.)
You'd probably be taking a bus back via Port Authority at 8th Ave & 42nd St. So, however long it takes you to get across town, plus the wait for a bus. Taxis crossing state lines will automatically double the fare, plus you'd have to pay for the $18(?) tunnel toll for the cab driver to return to NYC, as well as tip.
Just be very careful. The NYC streets are very dangerous right now, even in Midtown, where I live. Lots of stabbings and shootings. Do NOT take the subway.
This thread has a few of my posts from back in May, detailing some of the violence in NYC.
https://www.disboards.com/threads/nyc-insider-info-part-2.3837008/#post-62971677
It hasn't gotten any better. In fact it's gotten WORSE.
3 weeks ago, a fellow
Good Samaritan passenger tackled a man, who had just stabbed a woman twice, from stabbing her to death on the 14th St subway station platform. A few days after that 2 women were stabbed at the 135th(?) St subway stop, meanwhile there were 2 more unrelated stabbings a few subway stops north of that, a couple hours later by different people. Just a few days ago, the news reported 16 shootings in one night all around the city. I can't even begin to count the stabbings in and around the city - not just the bad sections. And an Asian person is brutally attacked almost every day on the streets. E.V.E.R.Y. D.A.Y. Normally I annotate all the examples I write, like the other thread. Just too tired right now.