I literally just did this over the past few weeks. I bought four ESP32-C3 minis on expansion boards (The expansion boards come with PH2.0mm connectors and built in battery charging management, so that I can add battery power next - already ordered the LiPo batteries. At the moment they’re plugged into USB-C phone chargers) and four SHT-41 temperature and humidity meters. I then installed the espressif development environment and (don’t shoot me, I was under time pressure) vibe-coded the setup for the ESP boards: they broadcast the readings every 10 seconds via mosquitto.

I also bought a barebones raspberry pi and made it subscribe to the mosquitto feeds and write the data to a sqlite database, and created a basic flask website that reads the data from sqlite and shows the graphs and the temperature readings to anyone on my local wifi.

My code is on codeberg - I’d be happy to share the link if any of this is relevant to you.