This is exciting to hear! Last I heard, Ecosia just wrapped Google's results. KAGI is pretty upfront about doing the same.
This will sound silly, but an absolute need-to-have for me is the ability to throw basic math problems into the search bar as a calculator.
I never reach for a calculator or spin up a separate app for it, or want to widget on my desktop.. instead, I just press the keyboard shortcut for a new tab in my browser and then just belt out whatever parentheticals I need.
This pretty much serves as the basis for my evaluating different search engines, if it won't handle the algebra for me, I have to move on.