The approach seems similar to what I spoke about before (scrape tzdata, although they scrape install zone files directly in /usr/share/zoneinfo). I’ve attached the csv output of that. 460 time zones, about 15KB code size. That is up-to-date with tzdata 2018d-1. Including a simple library wrapper, to (a) iterate over the zone names, and (b) return the posix string for a particular name, probably less than 20KB overhead.