Managed to get past the CTD:
-First I disabled my primary network adapter (basically to disconnect from the Internet)
-Then I started MSFS and it didn’t crash but got stuck because of not internet connection
-After that, with the game still running, I reenabled my network. Seconds later I got to the Installation Manager to download the 150GBish of updates.
Will keep you posted and what I find. My hunch is that its related to Steam/Microsoft save game corruption or something similar.
My Zendesk ticket ID: #99735