I featured TinyPilot a few days back which is open source, but they exclude the remote USB mount from their open source version, and their focus is more towards a subscription model. It will however do what most folks probably want, and it's big plus for the purchased hardware is its pure plug-and-play approach.
PiKVM on the other hand is fully open sourced (so all the functionality is available) with an added benefit that it can also (with some hardware interfacing) monitor the hardware LEDs and manage the ATX power of the remote device. It has more flexibility in working with versions of the Pi prior to v4, and can also work in read-only mode with the Pi's SD card, to help preserve it's life. PiKVM is at
https://github.com/pikvm/pikvm.
The video does a good job of highlighting some of the differences between the two KVMs and also explains why you'd want to use a KVM in the first place for remote devices.
See
https://youtu.be/TIrkEr2AeDY
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