It’s SSE from Penygroes, Caernarfon. I haven’t looked where the places you mentioned are, sorry.
E.T.A. I’ve just looked where Llanrhystud is … so no. Is there another Nebo in Cymru?
E.T.A.A. I’ve just checked and yes there is, but no @HuwJones, it’s the one in the north overlooking Caernarfon.