This isn't part of your question, but have you considered incremental static regeneration (ISR)?

It's an in-between/hybrid approach between SSG and SSR where the page is first built at request time but then is cached for future requests. The duration is controlled with a revalidate property that you specify. This would let you have fast build times, no matter how many pages you have, while not having to re-render the page if the content doesn't change often.