Well that was a nice surprise: my backup phone (Sony Xperia Z5 Compact suzuran) is setup with an unofficial build of LineageOS for microg. Lawnchair 2 launcher, lots of apps installed, 2 NextCloud accounts, 4 email accounts etc.
I have a test build of e-15-q and I forgot to wipe data / factory reset before flashing the /e/ ROM. When the phone booted up, all my apps, my Homescreen setup, my NextCloud and email accounts, were all there.
Most apps needed to confirm permissions when I first ran them, and accounts for a few apps - the ones which store their own passwords rather than use Account Manager (including Messenger, Twidere, Ebay, Garmin Connect) - had gone and had to be re-entered. Still saved my a lot of time in setting up the phone from scratch or restoring a TWRP backup. Colour me very happy 