

Wildcard is actually good these days because you don’t have to set up DNS entries for your hostnames.
It’s not security, just obscurity - but in the age of crawlers, it’s helpful.
Also, you can use it internally for services on LAN and because LetsEncrypt is a CA everyone trusts, you don’t need to register a local CA (like a FreeIPA instance) with all your devices- which sometimes isn’t possible.
EDIT: you can also use DNS01 challenges and instead of proving yourself by serving up a challenge response from a server, you prove ownership by adding a DNS TXT entry with the response. It is safer, from a security perspective, to use one cert per service.
Since Podman is based around systemd services managing the containers, why not have a look at systemd .service files? I know you can set dependencies in those and so you can say that your other containers can’t start unless gluetun successfully starts first.