This is exactly what Framer did before pivoting to a website builder, it might be worth looking into them. How will you be different than them?
We built it because we couldn't find something that would let our clients' content teams produce content for their sites without 1) either going off-brand or 2) pestering their devs for layout changes.
In my experience, most of what content teams work with are some forms of CMS, and the design tools usually deal with layout and creating generic sites that work with the data structure inside the CMS.