Puma is certainly fine as the app server - but normally you'd still have a proxy/load balancer/tls terminator/"ingress server" in front. Something like traefik, nginx, haproxy or caddy.
If (one of the) front-facing servers do regular http caching (a good idea anyway to play nice with rails caching[1])", you can probably "serve" the static assets straight from rails and let your proxy serve them from cache (if you don't have/need a full cdn).
