How do I know if GPU hardware acceleration is working?

I installed 11.7 Big Sur on my late 2009 MacBook Pro, which has integrated Nvidia Geforce 9400M graphics. I know later versions of MacOS have dropped support for older GPUs, so I want to know if hardware acceleration is working or not.

My dock is transparent and the magnification effect works fine, and videos seem to play fine on YouTube, but Activity Monitor shows no activity on the GPU column.

I know some of DosDude's patchers re-added support for older graphics cards, but I don't know if OpenCore did the same.

Is there an app or a tool I can use to see if my graphics are fully working?