To support SSR, is it necessary to use @tanstack/react-start?

const router = createRouter();

    const memoryHistory = createMemoryHistory({
        initialEntries: [req.originalUrl]
    })

    router.update({
        history: memoryHistory
    })

    await router.load()

    const routerHtml = renderToString(
        <StartServer router={router} />
    )

const router = createRouter();

    const memoryHistory = createMemoryHistory({
        initialEntries: [req.originalUrl]
    })

    router.update({
        history: memoryHistory
    })

    await router.load()

    const routerHtml = renderToString(
        <StartServer router={router} />
    )

const router = createRouter();

    const root = document.getElementById("root") as HTMLElement;
    
    hydrateRoot(
        root,
        <StartClient router={router} />
    );

const router = createRouter();

    const root = document.getElementById("root") as HTMLElement;
    
    hydrateRoot(
        root,
        <StartClient router={router} />
    );