I'm kind of surprised that Next.js -- being known for SSR and SSG -- isn't offered with a CDN solution OOB on Vercel; seems like a no-brainer.
Last startup, we ran Astro.js behind CloudFront and we were able to serve pretty large volume of public-facing traffic from just 2 server nodes with 3-tiered caching (Redis for data caching, application level output caching, and CloudFront with CF doing a lot of the heavy lifting)
We're going to put Cloudflare in front of our Vercel site and control cache for SSR pages with Cache-Control headers.