There's no way to have SSR'd gated content without paying a gazillion bucks to either netlify or next for role-based redirects.
Even if I would go for CSR'd content for the gated part, I'd have to fiddle with JWT tokens.
To handle users, I'd have to use a 3rd party service such as oauth, since zeit doesn't support users, and netlify's model is severely limited.
For a CMS, I'd have to again go for a subscription model.
Data and APIs are also another issue. There is no way to use something like Strapi since that needs to have a real DB behind it.
Now, to orchestrate the users for role-base redirects, oauth, payment gateaway data and everything else... I've no idea where to even start.