Could be better, but this is what I did:

    for i in `brew ls`; do brew info $i | grep -e 'Built.*with:' >/dev/null && brew info $i; done

Out of 144 formulas installed, I've only got one with an option (mpv --with-bundle). I hope the Homebrew folks will use that option as default, but I suspect they won't, and will recommend the cask instead. Which isn't really what I want, but ok.