see this is already a problem - you've sed "in its pure form". there is no other forms of bitcoin, theres only one. The rest of them are not forms of bitcoin but mostly convenience or price exposure solutions.
Discussion
I'm not saying there are other forms of bitcoin. Immediately after that I say that Bitcoin cannot be a cbdc, given it is used according to its rules.
But there are other applications which should help with some shortcomings of BTC itself. And even those must adhere to BTC principles.