It's sort of interesting. I have an old Underwood that I still use, though I need to find a replacement for the bakelite spacebar or how to repair it, since I broke it in half. Not sure I would really want to use it as my primary keyboard. The hard action and huge amount of force and effort to use it is so ridiculous compared to the MX keyboards I use for most of my typing. It is still fun to clack away on an old typewriter now and then.
More silly nostalgia kitsch like rotary cell phones and other retro tech conversions that are amusing but entirely non-practical.