I don’t know what your exact criteria for “sportswatch” is, but I’ve been very happy with my Bangle.js 2: https://banglejs.com/

This is not true. In fact, Guix doesn’t use systemd at all. When managing an operating system installation Guix uses its own init system called the Shepherd.

Elogind is a project extracted from systemd originally for use in Guix systems.