@mroach I also love obscure old devices. I have a Sharp MI-10 color zaurus from 1996. First PDA ever with a color display. Very undocumented, but supported applications, had an attachable camera and even a modem card and a html web browser. I did not get that to work yet but if I do, i will likely be the only person in this decade to have used this browser.
Overall I feel like there is so much to be done documenting the history of user agents!