openbsd has native support for 'ugold' temperature/humidity sensors - this does publish the measured values via mqtt

temphumi.py

#!/usr/bin/env python3
#
# https://gist.github.com/gretel/22b7b042ef0317d779e5d114710d1e17

MQTT_HOST='mqtt.jitter.local'

import subprocess
from time import sleep
import paho.mqtt.client as mqtt

def publish():
    r = str(subprocess.check_output(["sysctl", "-n", "hw.sensors.ugold0.temp0"]), 'utf-8')
    t = float(r.split(' ')[0])
    print(t)
    mqttc.publish("home/sensor/studio/temperature", t)

    r = str(subprocess.check_output(["sysctl", "-n", "hw.sensors.ugold0.humidity0"]), 'utf-8')
    h = float(r.split('%')[0])
    print(h)
    mqttc.publish("home/sensor/studio/humidity", h)

    r = str(subprocess.check_output(["sysctl", "-n", "hw.sensors.km0.temp0"]), 'utf-8')
    c = float(r.split(' ')[0])
    print(c)
    mqttc.publish("sys/sensor/svaha/cpu", c)

mqttc = mqtt.Client()
mqttc.connect(MQTT_HOST)
print('connected')
mqttc.loop_start()

while True:
    publish()
    sleep(15)