It would seem it takes in account a bit more than "visual similarity", otherwise I can't find a good reason for "@" and "U+1F582 (BACK OF ENVELOPE)" being that close.
Also, for years (decades?!) I wanted something similar in Word, for when I knew how to describe the symbol in words, but had a hard time manually searching for in the unwieldly UI. I can't believe that "insert symbol" window still doesn't have any kind of search capability.
I made a similar tool that in my opinion looks better and is more useful for finding characters. I feel that the tool the OP posted seems cool for short periods of entertainment, but isn't very useful for utility. Link to the website here: https://unicode-atlas.vercel.app
Also, for years (decades?!) I wanted something similar in Word, for when I knew how to describe the symbol in words, but had a hard time manually searching for in the unwieldly UI. I can't believe that "insert symbol" window still doesn't have any kind of search capability.