Looking for advice on using soil near former burn piles.

I bought a property last spring and there are 2 areas where the previous owners burned. I’m not concerned about branches, leaves and shrubs of course but more concerned about lumber (possibly treated?) and other things.

One pile has a burn barrel and looks like it was mostly sticks and small branches and what not but also noticed some bits of remains from lumber.

The other pile also had branches and stumps but there are remains of burned lumber, metal hinges and screws, a few small painted pieces, small amount of plywood, burned ash remains of papers (one page looked like it was a recipe), also small amounts of some fibrous materials that must have been insulation (I rolled it in my fingers and it just durned to dust and wafted away).

The first area is adjacent to where I would like to plant in ground garden beds. The second pile is adjacent to wetlands and is where I would like to plant things such as raspberries or perhaps out in a run for chickens.

I think there used to be goats kept there and the burned remains seems like they might be the old goat pen, but could also be old fencing or even from an old deck.

I carried a van full of lumber and partially burned lumber to the dump and paid to dispose of it. Also a van full of metal scrap to recycle. Then bagged up the ash and smaller bits and mixed it with other junk (mostly plastic, netting, broken pots etc) and brought to the dump as trash.

The soil seems very rich and healthy but I don’t know what I don’t know. The home was built in the late 90’s so lead is less likely to be an issue but treated wood could be and when someone would rather burn something than dispose of it properly then I also wonder what they did with things like used motor oil.

Any advice here? And affordable DIY tests for arsenic, metals and hydrocarbons? I don’t want to spend a fortune but do want some peace of mind and ensure I am doing things right. The property has well water which I tested and the quality is great. I didn’t pay to test for things like VOCs and PFAS though because it was like triple or quadruple the cost of testing for everything else combined.