I have an M1 MacBook pro and the screen (16") is wonderful. I have an external 4K monitor that was only 400$ and it is not as nice a screen, I'm not sure why-refresh rate? underlying technology?
Anyway, I mostly use it with no external monitor and find it very nice, including Xcode. You can also always plan on getting a monitor later when you can afford it. Maybe think about 16" instead of 14"? Possibly deals can be had on apple silicon machines that are not the latest?