@linuxdxs I personally would use MQTT for that purpose. It’s a very lightweight way of regularly publishing data through your network and fetching it with any device you want to. It’s also cross platform. You could use your android mobile as well.

I use MQTT to fetch data from and send controls to my tasmota plugs and it works very well.
There’s a module called MMM-MQTT-Bridge already published that could be used and my soon-to-be-published MMM-Tasmota would work as well as a basis.
On the Raspi’s you would need an MQTT server like mosquitto.
May not sound like the easiest way but on the publisher side it’s not more than a few lines of code.

Had the same challenge

3 DHT sensors on 2 different PIs

solution

on the PI’s I have a cron job wich runs a python program to extract temperature and send it via REST to a MMM-remote temperature

pseudo code json to send

            data = {'temp': round(temperature, 1),
                    'humidity': round(humidity, 0),
                    'sensorId': str(SensorID)}
            post_request(json.dumps(data), 'http://192.168.x.x:8080/remote-temperature', {'Content-type': 'application/json', 'Accept': 'text/plain'})

installed MMM-RemoteTemperature, 3 ids

			module: 'MMM-RemoteTemperature',
			position: 'bottom_center',
			config: {
				sensorId: '1',
				icon: 'home',
				showTime: false
			}
		},
		{
			module: 'MMM-RemoteTemperature',
			position: 'bottom_center',
			config: {
				sensorId: '2',
				icon: 'couch',
				showTime: false
			}
		},
				{
			module: 'MMM-RemoteTemperature',
			position: 'bottom_center',
			config: {
				sensorId: '3',
				icon: 'map-marker-alt',
				showTime: false
			}
		},

cheers

so, whatever u feel more comfortable with

once u set that up you can use your browser to invoke the function on the pi0 to return the temp…

once that is working, then u can build a module to do the same…
using my sample module might help on the last step

https://github.com/sdetweil/SampleModule

you could set up a little web server (using node js and express, or python) and then a module on the Magic Mirror could call that server to get the data