Any of these low-cost ESP32 development boards (ranging from ~$3 to ~$15 on Aliexpress) can be turned into a fully functional and secure crypto hardware wallet with colibri.diy - ofc fully free and open source
The project is still in the pre-release stage, but if you like tinkering with Arduino & hardware, check out the github repository for the firmware and build instructions.
Please let me know what you think!
