Finally beat this HORRIBLE little bug. A combination of @qiyi 's script which stabilized the machine so I could at least properly investigate it, adapting @RM9981 's steps to my own circumstances, and then running CleanMyMac over it to disable a bunch of things. Has anybody reported this to Apple's Big Sur dev team? Because if this had happened to , say, my grandmother, it would be basically a bricking, so they *really* need to get this solved before Big Sur goes gold.

"I need more help" The most useful lesson nobody will teach you, so I guess I will. "I need more help" is a really poor question. Tech support forums are overrun with people asking questions like "help I need to code a thing" and .... nobody really can help, because its not *specific*. When you do have a question, try explaining in detail what your trying to do, what you've tried to do, and then ask for help on how to solve single specific problems. "Where is a good place to learn swift" is a decent enough question because its asking about aolving a single specific problem, aquiring swift knowledge (I recomend Udemy by the way, lots of great courses and you can usually hunt around for a coupon code to get them dirt cheap). "How do I code swift" is a bad question , because your asking someone to pack an entire course into a single post. "I need more help", its not even clear what the question is! Have a browse around on Stack Overflow if you want examples of *perfect* tech questions and perfect tech answers. They have a super strict moderation policy, and what escapes moderation is almost always excellent questions and answers.