Enkianthus campanulatus is giving me great fall color on the north side of the house, where it gets a couple hours of sun per day. It needs some water in summer though.

If you can locate one, Hydrangea quercifolia 'Little Honey' offers golden foliage that prefers partial shade but still colors beautifully in the fall with not very much direct sun. The enkianthus is a great choice as well for a shadier position. Another wonderful and highly underused shade shrub offering great fall color is heartleaved Disanthus, Disanthus cercidiphyllum.

I have a quercifolia on the north wall of the house that is a deep red right now - same color as the neighbor's in full sun.

Disanthus is not a common plant. I raised three from seed some years ago.
Here's what the leaves looked like in the sun in the Fall a few years ago.
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Here's what the leaves look like in partial shade.

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The leaves are green in the Spring and Summer and look a lot like Redbud leaves.

To answer your question as to whether or not sun is needed for Fall color on a Hydrangea guercifolia or not, here is a picture of mine. It gets less than 3 hours of sun on a good day in the Fall. It has just now colored up.
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The plant is still young at three years and still in a pot. I will plant it out in the next few weeks.