I really would like see that Excellent results of Core Web Vitals on Apache, because for me its really tough to believe that you can achieve excellent results on apache, and i say it as admin, with at least 10+ years of administration experience. It might be possible at literally low users count on your site, but if you have busy site it would be really tough challenge to achieve it. The whole industry implement CDNs, Fast static content serving methods to minimize TTFB and LCP. The idea of doing apache+nginx thing is to lower load on Apache with serving static content when, your site is busy and apache handling lot of requests, i assume you have hosting account so might be worth to consider. I believe you when you use Cache Servers like Varnish or Service Cache like CloudFlare might be complicated to debug such thing. REDIS is object cache actually it's more backend thing rather front one like Varnish or Cloudflare, as well you can use it with Apache, its separate server/service, because it serves as layer between database and webserver, by literally minimizing queries to database when serve static content, it also often lowers LCP. It might be worth to try, i not tell you that you should do it, but you can consider it, at least won't hurt to try.