Seat Guru says GOL allows a personal item such as:
Bag or backpack with personal items
They point to this GOL page for more information but I find nothing to substantiate that.
Does GOL actually allow a Personal Item in addition to a carry-on?
Yes, Gol allows it and there is no specific restriction on its size and weight.
This is part of a conversation I had with GOL (I had to first explain what I meant by personal item with example of a camera or laptop bag):
GOL: I was checking and I see that you can take a little bag like the one with a camera with no problems additionally to the carry on bag
Itai: Great. Are there any restrictions on the bag? Size or Weight?
GOL: I don't see anyone, it only says little bag with personal items.