So I've been seeing these "sealed beam" headlights in a few places & was wondering if that's how all MR2 headlight's are? Where the whole headlight is a non serviceable globe, is that just a USDM thing or do all SW20s have that? I was hoping it would just be a normal H4 globe.

I think they can be swapped out for semi-sealed.  But others are more knowledgeable than me.

This was a thing on earlier SW20's My Rev1 has sealed beams, I bought some Raybrigs to replace as the light was very bad. I think from Rev3 onwards they are servicable, best thing to do is to have a look at the rear of the headlights!

Modern high quality semi sealed units that can take high quality H4 globes are vastly superior to the sealed beams units that were fitted to 30 year old MR2's. The difference is quite dramatic.
I am talking about good brand name stuff like Hella and Phillips (see pics), and these can easily be swapped over to replace the old sealed beams.
Modern globes also have the sharp cutoff on low beam for greater safety.