Definitely a grape, prb'ly whatever the local wild type is.

I have wild Mustang grapes, Vitis mustangensis, covering Hackberry trees on a neighboring property (up in D/FW). But the leaves on them are white and velvety underneath.

The leaves of yours don’t look like Vitis rotundifolia, Muscadine grape.

For fun, the neighbor’s vines in summer and winter. They make a great bird haven:

The only other Texas native I can think of is Vitis aestivalis, Summer grape, but I don’t think I’ve ever seen one up close.

ETA: Just saw this Texas grape I wasn’t aware of, Winter grape. Hmm. Instead of helping, I think I’m making it more confusing! Sorry, hope someone knows.

There are a few different species it could be, and they look almost the same, and they all have variation in their leaves. You would have to key this plant out to be certain which species it is. V. berlandieri, V. mustangensis, Muscadinia rotundifolia var. rotundifolia, V. rupestris, V. vulpina.

^^ Agreed, I'm pretty sure it's not Vitis mustangensis, which should have white, fuzzy undersides and maybe ~1/2" grapes.

Vitis rotundifolia has much toothier leaves.

The leaves also don't seem to match Vitis aestivalis, which are usually more lobed.

Vitis cinerea var. helleri might be a possibility?

Vitis berlandieri should have leaves that are slightly toothier, sometimes lobed, and with small tails.

Vitis rupestris should have toothier leaves, too.

And Vitis vulpina should have slightly-toothed, slightly-lobed, cordate leaves.

Vitis cineria var. helleri looks right.