Can potions of Occult Adventures classes-only spells be made?
Yes, no language restricts Brew Potion or potions themselves to only arcane and divine spells.
If you have a caster level of three you can take the feat, and make potions out of any spell you know of third level and lower whether that spell casting class and spell is divine, arcane, psychic, or whatever else type of casting comes down the road.