Most pages tend be just documents and fairly simple forms. Making SPAs and then having to worry about SSR is just making a Rube Goldberg machine in most cases. I think something like HTMX is a much better approach in most cases. You keep all your business logic server side, send regular HTML to the client, and you just have a little bit of Js on the frontend that knows how to patch in chunks of HTML in the DOM as needed. Unless you have a highly interactive frontend, this is a much better approach than making a frontend with something like React and adding all the complexity that goes with it.

No one cares about graceful degradation anymore. But you can sell management on SEO. Page performance is a key aspect of search engine rankings and server-side rendered pages will almost always have a much faster initial load than client-side rendered.