Yeah that’s exactly right! You have the proxy listen on 80/443 and use the subdomains to proxy to the respective other services that you have listen to other ports. Make sure those other ports are not open to the outside, though, as that would allow someone to bypass the proxy. In you example, you would change away from 0.0.0.0 to 127.0.0.1, which means the port is only open to the loop back interface, not the other ones. This happens accidentally especially when using docker for the app service. Also you should probably run some firewall to block all ports that you don’t wish to expose.
I’d really suggest you take a look at Caddy for the reverse proxy. It completely handles SSL certificate creation and renewal so you don’t have to do anything.
One big thing they’re used for is sort of multiplexing port 80/443. You have one daemon listening on them, and you can have multiple domains pointing at the same IP. The reverse proxy will figure out which backend service to forward requests too.
Proxies like Caddy and I think Traefik also automatically manage SSL certificates. In many cases you could have your application server handle SSL, but usually it’s a good idea to have dedicated software for this.