Can my military spouse ETS while on maternity leave (Her unit wants her to do a Chapter 8 which is not an option for us)?

If I were counseling her, I would advise her to extend through the end of the maternity leave plus maybe 60 days or so.
This does a couple things. She is getting paid while she recovers, and it gives time to address any service-connected issues that might arise that you need to document in her service records.
Chapter 8 is stupid if she is that close to ETS.

UNDer general honorable

that is a big yes