Device #1: Airnote. Measure Air quality
https://blues.io/products/airnote/ It's plug and play, I installed one at home and it works a charm.
Device #2: SolarCast Nano. Measure radioactivity
https://safecast.org/2017/12/introducing-the-solarcast-nano/ This one, I need your help to buy some batteries for it. 18650 I think, you might have some in stock!
Device #3: Helium Miner. Become an IOT LoraWan gateway and mine HNT
Network: https://www.helium.com/ Miner: https://uk.pi-supply.com/products/helium-outdoor-hotspot-miner-gateway