I found out now, SV actually did restore data.
But, it did not restore the apps.
On the 7a I installed f-droid and Aurora store, Installed my apps first, then SV restored the data.
Do apps, that run on a 4a not run on a 7a? Different CPU architecture? I can imagine this the only reason, why SV didn't restore the apps apk´s.
In short, if in trouble, on the new device:
Put your backup thumb drive into USB-C, install f-droid/Aurora from a local APK, install your apps while thumb drive is connected and SV restores app data from thumb drive. This is how i did now.