Just the great movies:
https://letterboxd.com/re2/tag/great-movie/films/by/release-...
You can then filter those by streaming service, but you need a pro account. Looks like 38 movies:
https://letterboxd.com/re2/tag/great-movie/films/on/amazon-p...
Apparently I missed the Buster Keaton movies:
https://www.rogerebert.com/reviews/great-movie-the-films-of-...
https://letterboxd.com/director/buster-keaton/
But that means 39 isn't quite right either since Ebert is saying all of Buster Keaton's films are great.
Anyway, the scraping was easy. The harder problem was parsing the html reviews (even with BeautifulSoup, the html is a mess), and then matching the reviews on Ebert's site to the correct movie, which I did via queries to tmdb and a lot of heuristics. There's nearly 8000 reviews and many have wrong years, bad titles, etc on rogerebert.com. It was a fun spare time project for a couple weeks.