Fairphone 3 and Android 10 adb backup Compatibility

I have read on [1] that Fairphone 3 comes with Android 10 installed on it. I would be migrating from an older device with Android 8.1 and I’d like to know if it would be possible to use adb backup to restore some apps’ data (backed-up from Android 8.1) to the new Fairphone with Android 10. See reference [2].

And I’d like to ask another question: Is it mandatory to create a user account on [1] to buy a new Fairphone or can I checkout just submitting my data without creating an account?

[1] https://shop.fairphone.com/
[2] https://www.xda-developers.com/adb-backup-and-restore-depreciated/

We are all users here and not employed by Fairphone, so I would say the way to find out is either to try and cancel the buying process before it is finalized or ask Fairphone customer support. I just tried and it seems to me what I get to read in the process makes it very likely that a customer account is not mandatory. See yourself:

I do have a customer account, but as you can see in picture 1, I still get the option to buy not using my customer account. And in picture 2, you can see that it is said that I “can create an account after checkout”.