the current way to go about it is to use TWRP backups until Seedvault (needs Android 10 APIs) integration is complete. Checkout this HOWTO and comments:
The gitlab epic you want to subscribe to is #31. Currently it looks like being postponed to after e-0.17. As Lineage has Seedvault integration from 18.1 up this might reignite efforts in /e/ when rebasing devices to Android 11