I planned to backup my apps/data from my old phone (LineageOS 18.1) and restore them on the new one (using IodéOS 6.0), using https://github.com/AndDiSa/android_backup_project/.
I’ve done the backup, but I can’t load them on the new Phone, because it needs « ADB root access », and I don’t find this option in Settings → System → Developer Options ?!
Is it possible to enable this option ? Perhaps it has been moved elsewhere in Settings menu ?
No. At least not if you are using an official IodéOS build. The builds that Iodé make and publish are user builds. adb root / rooted debugging is only available in userdebug or eng build variants.
Unfortunately this means that backups made using tools that require at least rooted debugging on phones running ROMs that make userdebug builds (LineageOS - with or without microG, dev / community builds of /e/OS, unofficial builds of IodéOS) cannot be ‘restored’ on to devices running official IodéOS builds.
This is possibly the most annoying ‘feature’ of IodéOS: it means there is no practical functioning way of backing up your Iodé device, or migrating from a different device or custom ROM to official IodéOS. Of course there is SeedVault, and we know how practical and ‘functional’ that is!
The alternative is to make your own unofficial userdebug build of IodéOS for your device
Thanks for your clear explanation !
I’ll re-install my old apps and restore data the old way, copying files, it takes a bit longer time, but it’s a good occasion to wonder if I ever need every app I’ve installed in the past 
Does your LOS have Seedvault Backup built in? That would reduce the amount of work.
LOS has it per se