Is there a way to set the NVIDIA GPU as the default GPU (disabling the Intel iGPU) in my laptop?

In Linux Mint Cinnamon, this can be done via a taskbar applet.
Pop! OS also has the ability to do this.

There's apparently this https://github.com/kz6fittycent/nvidia-optimus-manager
but the repo has been archived and IDK if it would still work.

An applet would be preferred, but a terminal command may be fine. However, I don't want something very complicated that would break upon doing an update.

There's an application called "Hardware drivers" (DoFlicky) that let's you install correct Nvidia driver. After install and quick restart Nvidia GPU should be working properly.

As for (totally I assume) disabling Intel iGPU there should be some settings to do such things in your BIOS but that's something someone more tech savvy should adress here