I have found vinegar an excellent weed killing tool when someone put down weed barrier and rocks. You don’t care about the soil in that case.
Otherwise a torch works great if there is no plastic weed barrier to burn.
I am removing all of the weed barrier slowly on my property- it is snake oil no matter where it is used. Nature will slowly build soil on top of the barrier in a few years and it will slowly degrade from wear and heat. Max 3-5 years before it is just a big mess in the PNW.