It's not Endeavour's fault (or Arch), if you're new to Linux, and you're running Nvidia, you're probably on X11. You can check this by running nvidia-settings in the terminal. You can see if you're running an X server (I think you're using Xfce, which is the default DE for Endeavour iirc). If that is the case, then you're on X11. In nvidia-settings, you can then configure the monitors, it's a bit fiddly, but I'm running (on X11 with Nvidia) two monitors with a left vertical monitor, at different refresh rates even, and it works.

Also, make sure you have the Nvidia drivers, and not nouveau.

that's an nvidia issue for sure. When I had my nvidia laptop, I had nothing but issues with it.

However... you need to install the nvidia drivers and nvidia-settings. There you can configure the monitors and it should work as expected.

edit:

It’s on me for choosing a broken distro but I kinda like it otherwise

There's nothing broken with EndeavourOS. I've had it for a long time and it served me well