Almost all of those are shortenings of longer words.
Wait, ASCII isn’t pronounced “ushy”?
Whaddaya know, I’m correct to pronounce PNG as “ping”! See what intuitive design can do for ya?
Years & years ago, in Windows 3, I used to use the suffix .gyf for bitmaps, as a way of personalizing the file name. I don’t know where’d I’d seen GIF’s before that, but I guess I had. I used the y because it evoked the word “glyph”–which of course has a gamma sound.