Via Mullvad VPN I managed to finish the download. After running the apt dist-upgrade command I did a reboot.
The Librem 5 does not fully boot any more, and gives this errors on a black screen and stops continuing to boot (note that I typed the errors below manually, so there can be spelling errors:)
I see around 12 times:
Nothing to read on input.
Next three times:
cryptsetup: ERROR: luks-xxxxxxxxxxxxxx: cryptsetup failed, bad password or options?
Then:
cryptsetup: ERROR: luks-xxxxxxxxxxxxxxx: maimum number of tries exceded
The whole sequence of luks errors roughly repeats four times.
Indeed, I did use the LUKS Crimson image variant.