Seelah’s hit rate gets pretty nuts later, especially when she gets the option to pick up a mount or divine weapon bond at level 4 I think. Her damage output explodes in chapter 2 with a certain sword with an AoE damage effect that probably hasn’t been nerfed.
Lann is all about shooting things really well, and can pick up feats to become immune to and allows him to perform opportunity attacks later. He has one ability that adds an additional attack during the turn it is used, along with another that basically grants him the pathfinder equivalent of advantage on his attacks for one turn. He transitions into a tank capable of fighting at range then.
A lot of the early companions are late bloomers. For example, Camelia’s damage output sucks until you pick up fencing grace, which allows her to add her dex modifier to her melee damage rolls. Then she’ll later get the ability to enchant her weapon with elemental damage, which gets deadly combined with elemental barrage mythic feat.
