"Technically, there are no links between Ogham and Ogmios, they have similar dounding names yes and it may be that one is derived from the other"
But what would a 'technical' link be? I can't see how one can be derived from the other and not be in some way linked?
"According to both Gallic and Irish myths Ogma was a warrior god, depicted as a wrinkled old man, wearing lion's skin cloak, carrying a bow and club"
I think Ogma (and Ogmios) are etymologically linked by 'Ag' (carve), so 'Ogham' could have come before Ogma rather than vice versa? I suppose it's possible that Ogmios and Ogma have no technical link, but the similarity is so profound that , as with so many deities, they are synonymously linked by the original word/thought/symbolism from which they were born, or from which they communicated their existence?