About the storage - you can always buy additional external storage (mechanical hard drives, SSD drives, large flash memory sticks) and archive less-needed files onto it, but you can't upgrade the memory after purchase.
It helps to not fill it up with movie and music files. Those can go on external storage devices.
Do you have any notion of what kind of "handout" materials and/or digital text books you'll be getting? If they are proper (and searchable) text-based documents, they should not take up too much storage, but if the profs are lazy and simply make PDFs with optical scans of text, they could suck up a lot of storage in a short time.
You should get at least one external drive anyway, and dedicate it as a daily Time Machine backup.
Allow me to quote myself from another (similar) thread:
"Oh - it might be useful to check out the requirements for using Zoom (especially with virtual backgrounds) as a kind of benchmark. - See https://support.zoom.us/hc/en-us/articles/360043484511#h_1d44b8c6-0031-4c8a-9300-8c1a722ba057
You might be doing a lot of that for a while.
I think using a physical green screen is less challenging for either MacBook model, but it gets much better results."
I have a new MacBook Pro and my wife recently got an even-newer MacBook Air. (I do not recall the exact specs.) Mine can do the Virtual Backgrounds without a physical green screen, but we learned that hers cannot. It has to do a lot of crunching to detect what is part of you and what is real-life background. It's not a big deal because even when possible, the edge detection (without a physical green screen) really sucks anyway. Misshapen heads with outlines that wobble like Jell-O, spontaneous amputations of waving hands, etc. A real green screen hanging behind you is much more convincing.
BTW - you can get a 100-foot roll of bright green 40" wide vinyl banquet table covering at a dollar store, for CAD$15, in my case. Enough for 5 generously large backdrops even if you use a double layer to even out the colour.