It's one of those names I find unattractive but really interesting, partly because it had such a long history of use here, and partly because the 'gurt' sound is so grim to my ears that I'm a bit baffled by its historic popularity. Yet clearly some people still like it enough to use it! And it has a great meaning. The Finnish form
Kerttu still seems to be something parents like: to me that's a prettier sound.
A common nickname for
Gertrude in the 16th-18th centuries here was Gatty, which was so popular it turned into a matronymic surname. I quite like
Trudy: I could see that getting some use, maybe, but I'd be very surprised if
Gertrude has a comeback.