(10 days later...for the record): Turns out choral covers of pop songs are more common than I'd remembered. It's just that the most relevant search term is popc

(10 days later...for the record): Turns out choral covers of pop songs are more common than I'd remembered. It's just that the most relevant search term is popchoir/pop choir, which wasn't obvious to me until I noticed it used in several video titles in sequence. These tend to be performed by less formal community choirs, which makes sense. And though many have mic setups, the point about choirs being difficult to record still applies. The interesting bit is that many European languages have converged on the same juxtaposition of the lexemes <pop><choir>, with the former consistently being a loanword from English. That is, there are lots of search results to be found by translating literally to terms like popchor (German), popkoor (Dutch), поп-хор (several Slavic languages), or popcoro (several Romance languages), plus hyphen and space variations.