Kagi, location set to United States:
Page 1: Biden, Williamson and link to an article Google hides campaign sites of Trump, RFK Jr. and other Republican candidates
Page 2: Biden again, Pence
No further pages. 5th result contains an article that claims to be linking all presidental candidate websites, but it's a Medium, hidden behind sign-up. I haven't find any result with a comprehensive list of the websites of interest. Kagi does aggregate results from Google and Yandex, so this is probably not too surprising.