Each Phyrexian mana symbol on a Permanent you control on the Battlefield will count towards your Devotion for that color.

A Brief Explanation of Phyrexian Mana

Phyrexian mana is a mana symbol introduced during New Phyrexia. It can't be generated or made -- it's a cost. This cost can be paid with either a single mana of the color or two life. It uses a mana symbol that is slightly different from the normal symbol for each color.

It came back in Kamigawa: Neon Dynasty and added a hybrid mana version. A Hybrid Phyrexian mana symbol can be paid in one of three ways: either color that is represented on the symbol or two life.

Understanding Devotion

Devotion appeared in Theros block and was tied to the Gods in that set. It counts the amount of mana symbols a player controls on the Battlefield of a specific color, and reads as "Devotion to [color]", based on the colors that your cards can be.

Sometimes Devotion counts the total number of mana symbols of a certain color controlled by a specific player on the Battlefield; sometimes it checks if a certain number has been surpassed.

Note: it does not count every mana symbol on the Battlefield, only the ones under the control of the player that is counting Devotion.

What counts towards Devotion?

Mana symbols of the color in question of any kind in the cost of a Permanent count towards Devotion. If one is counting Devotion to Green, every on that player's Battlefield will count.

Additionally, every Green Phyrexian mana symbol, every Hybrid Phyrexian mana symbol which includes Green as one of the two colors, every other Hybrid mana symbol which includes Green as one of the colors, and a mono-color Hybrid mana symbol (where the choice is one mana of a specific color or two generic mana) which includes Green all count toward Devotion.

If something counts two colors (like many of the Gods from Theros block do), a single Hybrid or Hybrid Phyrexian symbol will still only count as one for Devotion, even if it can be paid with either of the two colors.

One Important Exception

Lands, and the mana symbols on them, do not count towards Devotion. Mana symbols in Activated Abilities or reminder text also don't count. The mana symbols, whether normal, Phyrexian, or Hybrid, must be in the cost of the Permanent in question.

That means the Permanents which count are Creatures, Artifacts, Enchantments, Planeswalkers, and Battles. Tokens and Permanents without mana costs don't count towards Devotion either -- the mana symbol must be in the casting cost of the card.

However, a Token that is a copy of a specific card will copy all aspects of the card, which means it copies the mana cost and will count towards Devotion.

Final Answer

Yes, Phyrexian mana counts toward Devotion, as long as it's on a Permanent currently on the Battlefield, and under the control of the Player counting Devotion.