Are there runway distance remaining signs used outside of the United States (and territories)? From what I can tell by reading this document (p. 50), these are standardized by the FAA (§ 2-3-13), but not the ICAO.
Do these exist anywhere in SI units (e.g. meters)?
There is no ICAO standard for runway distance remaining. Some nations have their own standards: for instance, Germany has a sign reading "½" in black on a yellow background at the halfway point.
This EASA document indicates that:
ICAO is currently working on the runway distance-remaining signs for which EASA is following the developments and will review the outcome of ICAO's work.