This is mostly thought experiment. If there are existing tools/devices that can help with process of hiding/spoofing your real location it would be interesting to explore them too.
Assumptions: (1) adversarial have full access to your computer (OS, bios, hardware etc) before you take it to unknown location (2) you can take the computer anywhere you want (3) you can connect to any network via wifi or cable (4) you cannot remove any hardware from the computer (5) you cannot uninstall any software from the computer (6) you need internet access
How to pretend you connect to network somewhere else in the world?
How do you spoof gps signal, how do you spoof radio stations to look like you're in different place in the world? Is there anything else that can give you away if you hide in a room so that the camera can't give out your location?