Chope I also learned that the cloudflar minify feature is going to be deprecated in a few months time. Not a big issue for me, as I was interested in moving avatars to R2, which this ext seemed to suggest was possible.
Yes, I got upload configured for R2 using its native S3 capability. You need to be very careful with the settings - I think what caught me out there was that I'd added a trailing "/" at the end of my endpoint URL. Once removed, it worked just fine. I tracked that one down by error messages in my flarum logfile, so do be sure to check yours if you're seeing problems.