This comment is steeped in bias. The front end is not complex for its own sake, it’s complex because APIs are needlessly rigid: https://bower.sh/front-end-complexity
Delete the API, render your html on the server, problem solved.
If you're not building something like Gmail, Docs, or Figma (AKA an app that should be on the desktop instead of the web). Rendered HTML should be the way to go, even if it's just a gateway to a more complex infrastructure.