How do I disable my MacBook Pro’s internal screen?  

@mac_editor do you have anything to say about this? I mean, when I tried "sudo nvram boot-args="iog=0x0"" command in Terminal (found this from some old site that it could turn off the screen from my MacBook), it just disabled the purge-nvda patches... and when I applied them again, everything was like normal again (including my internal display being on despite not showing a picture). I keep encountering more and more issues with my external display due to apps thinking I'm using my retina display.

Posted by: @piipperi800

mean, when I tried "sudo nvram boot-args="iog=0x0"" command in Terminal

You overwrote whatever purge-nvda did there. Just use something like SwitchResX to disable the internal monitor if required. iog=0x0 doesn't really work anyway after wake iirc.

Also deleted your other post as it was duplicate/repeat.

@mac_editor, ok thanks, do you know any free tool that could do the same as SwitchResX? Not really looking to pay that much for an app to just turn off a screen.

EDIT: also, when I exit from a game like Sims 4, the second screen gets reactivated. Also my wallpaper looks like this when I disable my internal screen, is this normal?

I was also thinking you could add a setting to disable the internal screen right into the purge-nvda if you know how to do it properly.

@mac_editor, the problem with SwitchResX is that it doesn't really work with Big Sur. For example, if I turn off my main monitor, it turns my internal display back on. And same happens if I enter a game like Sims 4

May I ask, is there a reason why the purge-nvda can't run in docked mode?