Doesn't Signal already have backup? IIRC, when enabled it once per day saves all messages (encrypted with a backup key, which you have to write down somewhere) to /sdcard/Signal, and you can then use Syncthing or something similar to copy it to a new phone. If you put that /sdcard/Signal folder there before starting Signal for the first time, it'll ask to restore from that backup. WhatsApp has an identical local backup and restore flow (except that it gets the backup key from their servers, instead of requiring you to write it down).
It's a backup which demands that you WRITE down a very long numeric code, then manually copy files off and then hope your family doesn't lose all of it.
It's a horrible user hostile process which isn't even implemented for iOS.
To be fair (to iOS users, not to Signal), the device transfer procedure on Android is somewhat more cumbersome as a result.
iOS gets the smooth new device-to-device direct transfer of the backup while Android users need to copy the encrypted blob (~2GB for me) to the new device and enter the encryption key. Admittedly, it does still allow for more flexibility than on iOS.
It is nice that the iOS version has that, but it a major pain say, if you are asked to reset your phone and restore from backup.
The recent issue with the Apple Watch not syncing health data meant that to get anywhere I had to wipe my phone, I had no where to transfer my Signal data too, thus - all gone.
It's not ideal when dealing with members of your family who really don't want to lose data, and is probably one of the few things that stops me in my own situation going over.
I do understand that in some cases this is actually a feature too, so I am not discounting it - just in my case this specific reason makes it really hard to justify a move over.
Just annoying that there isn't really a viable alternative anywhere at the moment :(
If iOS had that same option of a encrypted blob option then that would have solved my issue with the phone restore!
