Quote from: OP
2021 CKD-EPI in european unitsThat is an oxymoron.
If it uses different units for inputs and/or outputs, then the equation will be different, and it is no longer the 2021 CKD-EPI equation.
It is now the jinjon equation, and since jinjon does not have the reputation (or published, peer-reviewed papers) of the National Kidney Foundation, no-one will know what that is, and no-one will use it.
So stick to the 2021 CKD-EPI equation, in its original units.
See, for example: https://academic.oup.com/clinchem/article-abstract/68/4/534/6509513?redirectedFrom=fulltext