Systemd Daemon in Python with watchdog support

Probably, you could use sdnotify python module which is a pure-python implementation of sd_notify protocol. Actually, the protocol is rather simple, so the module implementation is quite short.

To use watchdog machinery you should add WatchdocSec=<smth> to the unit file, and then send WATCHDOG=1 messages on a regular basis from your service. Check Restart= option as well.