Last night I tried updating to Dawn using the apt sources.list file. I ended up with the keypad for entering my encryption password, but no touchscreen input and external keyboard didn’t work. I ended up reflashing my phone. Anyone else tried this? Is this a known problem?
The only keyboard related issue I could imagine was that I was using Squeekboard before the update, but I did that with an update to Crimson via apt sources.
FWIW, the PureOS update popped up and I happily tried it out. It worked out well. I decided I might as well try out the updater before applying my backup.