Many of the first results on Ecosia show american websites such as Expedia or Kayak.

Bonus points if they also have trip options with Canada to Mexico.

I have a friend who wants to go from Toronto to Montevideo

Booking.com is originally Dutch, with still lots (probably most, don’t know) of work and revenue in Amsterdam. Although it became American owned few years ago. However, still less American than most fully American sites.

Novasol is Scandinavian, might be useful too, but afaik not in all countries. https://www.novasol.com/

https://www.hostelworld.com/ for accommodation.

Didn't Booking have a controversy due to advertising/financing of illegal Israel settlements in Palestine?

Check out any of these, also this one (shows too whether the parent company is European or not)

Don't forget also allowing a fake posting of 10 Downing Street as available accommodation, allowing fake reviews on it and taking payments for booking it LOL