This looks really interesting! Tangentially related if anyone is interested, I recently wrote[1] a pure C (no external dependency) version of coordination free, k-ordered 128-bit UUID Generator library which is inspired by snowflake but has bigger key space and few nifty features to protect against clock skew etc. The 128 bits are split into

  {timestamp:64, worker_id:48, seq: 16}

where the seq is incremented if the unique id is requested within the same millisecond.

[1] - https://github.com/beyonddream/snowid