x4 Birth of Meletis x0 Wall of Omens seems really weird to me
If we assume that etb tutor 1 plains is exactly equal to drawing 1 card then

Meletis Pros:
- Gain 2 life
- If they use creature removal on the wall you still get 1 devotion for a bit

Wall of Omens Pros
- You don't have to wait 1 turn to actually get the wall (can block immediately)
- The nontoken permanent doesn't self-destruct after a few turns

The lifegain vs getting the immediate wall seems about equivalent but getting to keep the non-token permanent forever seems like a big upside in favour of Wall of Omens. Not only does it mean you keep the devotion forever but also if you draw e.g. Teferi/AstralDrift/Yorion much later you still have a value permanent to bounce/flicker.

And then importantly I also think that etb draw 1 is actually better than etb tutor a plains.

Another idea for the yorion build is to play a SFM package
- SFM->Skull is a fine wincon for the kind of midrange/control backup plan with thin ice / teferi etc etc in the lategame with Nykthos mana you can bounce and replay it
- Yorion can blink skull to reset it or blink SFM to search another equip
- Yorion out of the SB gives reliable access to a flying creature to equip
- SFM can search for a white equip e.g. Maul of the Skyclave to add more devotion