(If you would like to add your project's name to the list, don't hesitate to send us an email.)
ArduPilot Project is an Free Software autopilot system for various vehicles: multi-copters, helicopters, planes, boats, submarines, rovers… It uses Monocypher to secure its bootloader.
Joulescope is a precision DC energy analyser. It uses Monocypher to secure firmware updates and sign calibrations. They also wrote Python bindings for the host code.
Kryptor is a file encryption tool that aims to be a better version of age and Minisign, to provide a leaner, user friendly alternative to GPG.
Signify implementation in PicoLisp (Signify is a file signature/verification utility).
Skudra is a clone of ix.io, implemented in PicoLisp. It uses Monocypher's BLAKE2b implementation for hashing.
The Tillitis Key is a USB security key inspired by measured boot and DICE. It uses Monocypher in some of its associated applications (a signing oracle and an SSH client token).
Wireguard (IK pattern) implementation (from the Noise Protocol Framework) in PicoLisp.
World_Gate is a platform to build, run, and share a multi-agent strategic environment. One of its applications is to run tabletop games on a network of computers. It uses Monocypher to secure its online communications.