Professionals using multiple machines waste time swapping cables or re-pairing Bluetooth devices. A software solution could share inputs across computers over the network.
Build a low-latency tool that works across OSes, with hotkeys to jump between devices and synced clipboards. Power users would pay for features like file drag-and-drop.
Launch with basic keyboard/mouse sharing between two PCs, then add multi-device grids and touchpad passthrough.
The risk is hardware makers locking down input protocols or bundling similar features.