Comment by GundersenM

Yup, agree, this is the problem of having a legacy monolith RDBMS that needs to be rewritten and split apart. It's tempting to throw every new fancy technology at the problem when that is suddenly an option, but it's better to focus on the goal of splitting it apart only. If you have split it out, and it's now simple to convert to ES CQRS, then you are probably in a situation where you don't need to do that, as it works quite well.