I’ve just upgraded my encrypted FP2 running Fairphone Open from 18.04.1 to the “preparation update for Android 7” 18.04.3, using the OTA Updater, without any obvious problems. (Posting a success report in case anyone else was apprehensive of a rough ride on an encrypted phone, given issue #66.)
The 18.04.3 update is described by Updater as “This intermediary release prepares the Updater app for the upgrade of the operating system to Android 7.” So I wasn’t expecting any visible new features, and didn’t get any, but am now being offered 18.10.0 via Updater once again. 18.04.3 has a new kernel build (dated Nov 22), dunno if there are functional differences. Android security patch level remains at 1 February 2018, unsurprisingly.
I haven’t yet done the actual update to Android 7 (18.10.0); I’m waiting for a point where I can afford to be without my phone for a day or two if it all goes wrong. I appreciate that https://code.fairphone.com/android-7/ now has some guidance for those with encrypted phones.