2 things not clear - activation post cutoff date is possible or not; when they claim won't be selling it to customers - does that count for OEM? also one can downgrade from Win 11 to Win 10 at the time of installation, isn't it? Win 11 and Win 10 keys are interchangeable.
if OEM keys are available, I'm sure there are sites which provide untouched MSDN downloads of Win 10/Win 11 or older versions. One has to get the untouched version if the same download option from MS is blocked starting Tuesday.