We already have alot of unit and integration tests as high coverage was a primary metric from the start. I'm not convinced on the value of alot of the tests though so this could be somewhere to focus on.

I have introduced E2E/UI testing using TestCafe which benefits the relationship between Devs, Quality Analysts, and Business Analysts. Mainly because it forces all three parties to work together to define the UI level testing up front which acts as a contract when signing off completed work.