Unfortunately that’s one area I am bad with, I tend to use reverse_proxy for most such as Baikal running with the ckulka/baikal Docker image (which runs Nginx or Apache), otherwise I only static sites.

I’d start by looking at Baikal’s config for Apache and Nginx, sabre.io/baikal/install/ and comparing to the directives for Caddy, caddyserver.com/docs/caddyfile/directives and

Since it uses PHP, it will need that, caddyserver.com/docs/caddyfile/patterns#php

Upon my searches I came across this, it talks about running Baikal with Caddy specifically. github.com/caddyserver/caddy/issues/497

I hope that this provided some helpful directions.