Can base editors be anything else than SpCas9 and SaCas9 variants?

Question

I found out that only variants of Streptococcus pyogenes Cas9 (SpCas9) and Staphylococcus aureus Cas9 (SaCas9) are used with adenine or cytidine base editors, and I was wondering why.

Can Neisseria Cas9 be fused to adenine or cytidine base editors as well?