Single option (?)
We didn't eat there (we had plans to eat in Museu do Pão, in Seia), but noticed that this seemed to be the only restaurant in Piódão, and, to be more precise, the hub of the touristy organization that keeps the village alive.
It looks nice (though not well integrated in the surrounding architecture), but it was all that we could appreciate.
PS - Browsing internet, we may find three more restaurants in or near Piódão (Fontinha, Delícias do Piódão, Solar dos Pachecos).
I don't know if they are new (the boom of tourism...) or so discrete that we didn't notice them.