Ok so I got around this by installing an old version of speedtest I found online (it’s version 1.0.14.1 - the second ever speedtest desktop version released in july 2017). What happened was, the installer this time prompted to install Microsoft visual c++ 2015 (newer speedtest installers never asked). And it worked!
But whether newer versions of speedtest will work now since visual c++ is installed, idk honestly because I haven’t tested. Nevertheless, I’m glad I have a working app now.