I run 25 meters AOC HDMI, the problem was to pull it through pipe in the floor to the living room - those connectors are quite bulky. Some AOC cables come with mini-hdmi and, an adapter to the full size, but it wasn't available for HDMI 2.1 at the time. Works flawlessly. To switch between display on the desk and living room I run a small DIY java app in windows (shouldn't be a problem to run it on Linux), MQTT + home assistant as a remote app. I didn't play with CEC.
More interesting is a USB setup at this distance. I picked Ethernet - USB 2.0 converter and a simple USB hub with external PSU in the living room, $30. This enables BT, xbox360 dongles, keyboards. I didn't go with USB 3 as its expensive and unnecessary.
EDIT: It's easier to find under 'usb extender over ethernet', and I double check mine ATEN UEC260 costs closer to ~100$ now, way more expensive compared to what it used to be. It requires a dedicated CAT5 cable, it cannot go through any networking devices.