The good news is that after three days of tooth-grinding and a dozen tests from #reddit, I finally solved the third day's #AdventOfCode puzzle with numbers coordinates and surrounding symbols.
The bad news is that this puzzle, like any other, has a second, more complicated part.
@toby3d if you'd like a step-by-step walkthrough of each puzzle, I've been writing up those solutions on my site: https://advent-of-code.xavd.id