How can I do this? I want 2 split buffers with 2 contiguous parts the same file that always scroll in sync.

Maybe there's a package for this already or some clever solution? I want to have 2 (vertical) buffers open with the same file, with the right buffer containing what comes just after the bottom of left buffer. Then when I scroll in either buffer, the other will move too, so that I'm always seeing one long(er) continuous portion of the file on my laptop's unrotatable wide-ass screen. Does that even make sense? Thanks for reading!

Try `follow-mode`

Wow! Yes! Thank you!

A non-obvious thing about `follow-mode`: you can use it with more than 2 windows! If you create 4 windows with the same buffer, `follow-mode` will show you 4 contiguous parts.