I’ve been positively suprised many times, guessing for these bangs as well, very often they tend to be exactly as one would expect, even for sites in my own native language: norwegian, there are bangs for the more niche sites as well.

When I want to look something up in the norwegian Wikipedia I do !wno, for english just !w or !wen (and if I for some reason unbeknownst would want search in another language, it would be just a language tag away), I was very happy to see bangs for both the online norwegian dictionaries I use (!naob and !norsk), and some of the nicher sites, though, maybe not quite so niche here in HN: !dfw (Dwarf Fortress Wiki), even !nhw (nethack), etc.