So, nearly all of new ranger feats states requirement "Warden Spells", which intuitively makes you look for "warden Spells" feat... which... doesn't exist.
And after some thorough search you finally figure out that real requirement is to pick "heal companion" feat, which grant you first warden spell, and focus pool of 1.
It really creates a confusion, and i think need some additional explanations and perhaps some minor rework on how you grant spells to ranger.
Gravity Weapon also works as an entry Warden Spell.