I could not get it to work when I looked into it last, for Gimp I actually installed it globally, I think neither Chrome or Firefox uses the system Harfbuzz. Going by the dependants of Harfbuzz on Arch [0] it might be possible that it works in Chromium with a custom Harfbuzz, but it is not something I have tried. And since it is still experimental it is not built by default in any distribution I know of.
[0]: https://archlinux.org/packages/extra/x86_64/harfbuzz/