There's a project that did that but for a different purpose - a network KVM using a Pi4 - https://mtlynch.io/tinypilot/ https://mtlynch.io/tinypilot/ It had to

There's a project that did that but for a different purpose - a network KVM using a Pi4 - https://mtlynch.io/tinypilot/ https://mtlynch.io/tinypilot/ It had to use the one USB-C connector that's used for power for emulating the keyboard and mouse since that's the only one that supported USB-OTG. So you kind of either need PoE or another adapter to both power the device and be able to hae the Pi act as an input device.