Here are some ideas I have:

Enhance his Fang over Fang jutsus with a lightning style. This addition would amplify their power and potentially create an area-of-effect lightning strike upon impact.

Introduce a hound summoning ability. It would be intriguing to witness how he can combine his skills with another dog to create unique combos.

Explore sound-based jutsus. Given his connection with Akamaru, incorporating barks and howls into his jutsus could be fitting. For example, they could unleash a powerful sound wave through synchronized howling.

Allow him to unlock up to 2 inner gates. This would grant him access to heightened physical abilities and add an extra layer of intensity to his battles.

I'm curious to hear your thoughts and if you have any other ideas!