I guess I'm not quite understanding what you are looking for? Any harness system will incorporate using a lineman's style attachment so that you can work hands free.......unless you know something I don't a lineman's belt/rope will always need to be unhooked if you plan to climb beyond limbs.
What you can do to remain safe if that's the issue is to have 2 belts/ropes attached to the harness and attach the unused one above the limb while you are still attached below. Once the upper one is secured only then do you release the lower rope/belt.
There are safety systems that allow you to be hooked to the tree from ground to stand height but they are only fall restraint systems and not a hands free lineman's style.

I'm not aware of anything like you describe.

I use the harnesses that came with my Summit stands combined with the lineman's hook-up and safety rope with Prussic hitch.
Works great and I'm no squirrel.