@Stan Galat You're absolutely right, the pipe wrench did a number on the hex nut, but thankfully I had backed off before it was stripped too much. Argh I feel like an idiot- I'm not sure why I wasn't thinking about combination wrenches... the best deal was a set from Harbor Freight like you'd mentioned. Oddly the 30 mm was a bit large but worked (the 27 mm definitely too small). Anyway, I'm happy to report that I got the pulley wheel off. Thanks for your guidance & photos.
@Robert M Yet again I feel like an idiot- I'm not sure why I hadn't noticed that EVEN AFTER inspecting it for a clue of how to keep it in place!! I'm feeling like a monkey that's failing a spacial IQ study. Also thanks to you for tips & photo.
After all that, and applying the teflon tape to the threads, I think it might still be leaking oil just as much 😳. But hey, this is part of "the madness," part of the leak hunting process, and if nothing else I'm happy with what I learned about my car along the way.