I spent more than I would have liked trying to install Debian 11, including some attempts inspired from this thread and from Debian 11, Gen12th : Wifi working? - #9 by disposedtrolley … then luckily I found out that
https://wiki.debian.org/InstallingDebianOn/FrameWork/12thGen was apparently updated since @John_Grow posted it (?).
Following instructions there now works like a charm. In particular, you need a recent kernel and manual download of missing i915 firmware.