Is it more difficult to get 100% need-based aid at a need-aware college for international students (say, Williams or another top 50 college) than getting into Harvard, Yale or Princeton, which are need-blind for international students? I know that MIT and Amherst are too, but they’re not relevant to the question. I have very little idea of the competitiveness of financial aid for international applicants. Does it vary a lot by college?
Any university in the US that meets full need for international students is going to be very highly competitive for international students. Also note of course that they will meet what they consider to be full need, which might or might not correspond to what you think that you need.
There are need-aware universities and LACs that meet full need for any students that get admitted. I don’t see any reason to expect admissions to them to be any more difficult than somewhere like Harvard or Yale or Princeton, but all will be very highly competitive. If you are the top student that applies from your country, or from your part of the world if coming from a small country, then you might have a good chance.