today i learned that linking a new device to your signal account requires a working camera on the device you're linking from. i had been using the fork Molly, which lets you enter the link uri manually if needed.
a bit of a bummer, since my android vm does not have a working camera, so it seems i need to maintain an actual android device that does have a camera in order to use signal on desktop linux / nura. (i left molly because it stopped getting updates.)