M20 has a cycle of legendary creatures at Rare.
M20 has a cycle of legendary creatures at Mythic Rares (the Cavaliers).
The M20 Leylines have reasonable devotion and are great Rares.
Ravnica III has a complete cycle of uncommons with reasonable devotion.
Throne of Eldraine has triple mana 3 CMC legendaries at Rare. Blue and Red require more mana.
Throne of Eldraine also has a complete cycle minus one that is not a permanent at 4 CMC. This is the best selection for Guild Devotion.
There are also Mythic Rare legendary artifacts with good devotion
Throne of Eldraine also has an incomplete cycle of uncommon legendaries at 2 CMC.
The Theros II Gods are triggered into creatures by devotion, but don't provide devotion by themselves, which is fine and consistent with Theros I.
The Theros II Demigods get Power or Toughness from Devotion and have reasonable devotion.
There is also an incomplete cycle of Rare legendaries in Theros II with reasonable devotion.
Green got the lion's share of devotion so far.
There are a few other cards that are not in a cycle.
And most of the planeswalkers have reasonable devotion. I only show a few here.
Here are the current mana rocks. Ikoria does not have any.
