How about reversing that procedure and cloning your data volume to an external drive that's already got macOS installed on it?
An interesting idea....
I've been discussing this question with Mike Bombich, but I"m at a dead end, because I haven't got Big Sur and can't see how CCC reacts to it.
Would you please post screenshots of the options you're offered in CCC's "Copy All Files" and "Copy Some Files" drop-downs with Big Sur selected as your source volume?
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
