1 and 3: use caddy. I prefer the config format of caddy over the toml files used by Traefic. and caddy 2 even has an api for that Purpose. Caddy is rock solid.

1 and 3: use caddy. I prefer the config format of caddy over the toml files used by Traefic. and caddy 2 even has an api for that Purpose. Caddy is rock solid. 2: depending on the use case you may get away with an wildcard/catch all dns entry. If customers shall bring their own domain name, they will have to create an cname record anyway.