Wikipedia Apellai

You see! Telemachos is an Apellax.
Apollo, Maturing, Initiating Rites, Assembly, Solstices and the sun are all connected in Pyrgi!

Yes! We found the place of assembly en much more!

The surrounding wall at Pyrgi

The word is derived from the Ancient Greek word pélla (πελλα), "stone", and it appears in some toponyms in Greece like Pella (Πέλλα). The Doric word apella (απέλλα) originally meant wall, enclosure of stones, and later assembly of people within the limits of the square.

So, let's google some more and see if there is a good hint about this feast.

When a pubescent was received into the body of grown men, as a grown Kouros (male youth) he became απέλλαξ (apellax, "sharer in secret rites") and he could enter the apéllai.

Apella means wall or inclosure and the people within form the assembly! That is exactly what we found at Pyrgi, a surrounding wall, an inclosure of stones, original meaning wall!

Apella

Apella means wall or inclosure and the people within are the assembly! The wall or inclosure is the assembly, and the assembly is also the place of the 'Square'! The platform is a square and it is within the inclosure!

This is exactly what we found in Pyrgi.

And there is more about Apella.

Yellow: The surrounding wall at Pyrgi