React SSR to Fusionauth Freemarker Templates

We use Fusionauth to do authentication. Fusionauth is written in Java and uses Freemarker template for UI.
We have all our theme components in React using an adapted private material UI library (private NPM).

We would like to use React SSR (maybe using Next.js) to generate the register, login, logout, forgot password themed pages (in freemarker) and then upload the theme files to Fusionauth using the fusionauth API

Fusionauth API
https://fusionauth.io/docs/v1/tech/themes/

Discussion with Fusionauth team
https://fusionauth.io/community/forum/topic/199/oauth-login-pages-in-react