Biproducts in pointed, non-linear varieties
Determine whether there exists a non-linear variety with a non-zero object X for which the canonical comparison map Y_{X,X}: X + X -> X × X is an isomorphism.
References
We also turned certain questions which we currently are unable to answer into exercises; these are labelled 'ANK' for 'answer not known'. Is there are non-linear variety with a non-zero object X for which yx,x : X + X -> X x X is an isomorphism?
— A Homological View of Categorical Algebra
(2404.15896 - Peschke et al., 24 Apr 2024) in Exercise 4.2.13 (Biproduct in a pointed variety) - Section 4.2