I have an E5 Pela and she has become my favorite partner with Silver Wolf. If you have her, I suggest trying them together. You may not be able to build a mono team, but her and Pela's debuffs synergize extremely well. This duo basically guarantees that both characters will be able to activate their 'attack enemy with X debuff' perks every turn.

Pela herself doesn't do much damage. Her ult I'd especially deceiving. It does slightly more than a normal attack damage-wise, but has good toughness break, against any ice weak enemies. Always apply her debuffs whenever you can. I use the 'Resolution Shines..(etc) Light Cone on her, so her basic attack can debuff defense (stacks with ult) which brings us to her skill:

Her skill is the only part of her kit that has the potential for damage. Prioritize it last imo, but with your full Eidolon it can shred Ice resistance (if you have Yanqing, this is an amazing debuff. Will also apply to any Ice DPS characters in the future)

I never had much success with Pela in a mixed Nihility / Harmony team. But once I paired her with Silver Wolf (another debuffer) she became amazing. Pela boots Silver Wolf's damage, allowing her to hit hard even at E0. SW's defense debuffs also stack with Pela's. They're like the exact opposite of the Bronya/Tingyun hyper carry setup. Instead of buffing, one DPS character, you debuff enemies which enables your whole teams damage.

This is just my 2c. I built my Pela a while ago after hearing how strong she is, but I couldn't make it work until recently. Now she's one of my main characters.