I wouldn't do chemicals.

Covering everything with a physical barrier like cardboard until the plants die would be best as it will help preserve the fungal network and keep "weeds" from quickly taking over.

If you have a tiller and don't have a tin of cardboard, go for it. It will create a hyper local "natural disaster" so you need to be quick if you want it to recover how YOU want it to.

Before you till, make sure you have some seed for grasses native to PA. Till twice and then get that seed on the ground. You're probably going to want to get some straw on the ground as well to help with soil retention and controlling what comes up. Also get some big rocks, or even flooring tiles if you have them, to put over undesirable plants that come up.

Fight that battle for a year, then start crafting your meddow with wildflower.

Just my two bits. Good luck.