In the meantime I called Apple support to get help. I said right away that I am an IT professional who worked as sys admin in the past and that I would like to talk to experts. And they forwarded me to „experts“. The first said: „Forget about full restore, won’t work. Create a fresh install and manually (!) copy individual files from time machine to your mac.“ Second person told me to buy a new Mac with 2 tb ssd and restore to that. I asked her if it was possible to restore to an external ssd via Carbon Copy Cloner? As I did in the past half a dozen times. She told me she definitely does not recommend that path as she cannot recommend third party apps (?!?).
I did not try that option immediately as I heared a few years ago that latest MacOSes do not support booting from external ssds. And so I didn’t think of this option. But some research and I found out that indeed it is still possible, but you have to go some extra steps.
So if this wouldn’t have been possible I would have had spent two weeks to restore my machine. Or bought another machine with 2 tb just to restore from backup.
PS: I spent almost 5k Euros for this maxed MacBook Pro with 64 gb. Plus Apple Care. I didn’t want to buy another Mac just to restore from backups.
PPS: All of this was shortly before a very important presentation. So I was stuck with my work laptop (windows machine), and I am 90% less productive with it as it lacks my tools. Yeah, shouldn’t have screwed my main machine just before a super important milestone. Lessons learned.