These ESP devices are smaller than my thumb, simple, and cheap. 

They can run as mini-servers, come with built-in Wi-Fi and Bluetooth, and can even be turned into multi-sig Bitcoin wallets. 🤌
https://image.nostr.build/7b9b0b2c2244c73364a42d11d1c83e282d0ffb25e1d7ceb7968da4d71dba253f.jpg