My mouse is to the left of my keyboard, are there any right-handed programmers ?

No, us righties just tape stuff from stack overflow together. I don't think that counts.

Why would you strain your wrist? You don't need to have mouse strictly perpendicular to the display, it can sit at an angle and you only move it relatively to the "resting" position. I use large and ten-key keyboards everywhere and my mouse has at least 20-30 cm of free space to the right side of keyboard - no fatigue issues at all and my wrist on mouse hand is always straight.

I'm fine with the classic PS/2 layout on desktops.

But I do have a problem with laptops that have numeric keypads. Manufacturers seem to add them to their higher-spec products (the ones that are developer-worthy) in order to signal their higher value. When I really would rather have the option to not have it and let my hands center themselves under the screen.

You would find plenty of people who might argue that using the mouse would slow them down. I'm no keyboard purist but I do like an interface where I don't have to take my hands from the home keys. Also if you consider laptop keyboards the trackpad usually sits just south of the space bar keeping it nearer the hands.

That's true I've heard some people say they basically never use the mouse. I wonder how feasible this is with MacOS in its current incarnation.

unfortunately MacOS has a lot of keyboard shortcuts that are different depending on what application you're in (vs windows)

also there's a lot of annoying little things - if i'm typing in one space, and switch spaces, my typing cursor is still off the screen until i bring an app in the current space in focus

you can still do it, but there's a lot more context-specific stuff to be a keyboard poweruser on MacOS vs windows/linux

I found this was true for me after a while. I also noticed that, while typing, my hands were not in front of me but off to the left, which caused further stress. I've switched to a numpad-less keyboard and my pain has decreased.