Thank you for your quick reply.
1. I am afraid this is not an option because of react's hydration mismatches, and, more critical, page load content layout shifts
2. This is most likely what we'll build, yes, though the cache cardinality could become a problem. Any ideas which reverse-proxy to build on top of?
3. Stale-while-revalidate it is. Just a TTL would to expose uncached content to search engines.