How can I connect a keyboard, mouse and controller to a PC 15 meters away?

I'd start with wireless if the PC and seating area are close enough in a straight line. The cable route might be 15 meters even when the actual wireless distance is much shorter.

A 2.4 GHz keyboard and mouse or Bluetooth peripherals could work, depending on what your PC supports. Check the controller's wireless options too. Walls and interference can make a difference, so range isn't guaranteed.

For wired peripherals, look for an active USB extension rated for at least 15 meters, then connect a USB hub at the TV end. A powered hub is worth considering so the devices aren't all relying on power from the long cable.

Check the extension's USB version, power requirements and compatibility before buying. Active cables can get pricey, so compare the total cost with other options.

A USB extender that uses Cat6 cable is another option. Run the network cable alongside the HDMI and put the extender's USB end near the TV, with a hub if you need more ports.

Make sure it's an actual USB extender kit, not just a passive adapter. Check that it supports the USB devices and distance you need.

You could also look at a fiber USB cable with a powered hub at the TV. That keeps all three peripherals near you and gives you more ports, though you'll want to check the cable's supported USB version and whether it works with a hub.

A dock near the TV might be convenient if you want a more permanent setup. There are wired and wireless options, but check how each one connects to the PC and what ports it provides. A wireless dock with a dedicated receiver may be worth considering if input latency matters.