This one hundred percent. Give favored souls abilities that are similar to warlocks since they're supposed to have a personal connection to their gods. And favored spells similar to pact magic that matches the diety:
Vulkoor - deception (invisibility, displacement, etc. Maybe a scorrow form).
Lord of Blades - mix bag of offense/defense (artificer barrier spell, reconstruct spells).
Silver Flame (Divine Punishment, banishment spells, Order's wrath).
Amaunator (nuke spells - sun bolt, sun beam, other laser spells)
Court of the Dead (healing spells for undead, necromancy / insta-kills).
Sovereign Host - Additional healing/support/curative spells.