Хорошие новости, Let’s Encrypt анонсировали поддержку wildcard сертификатов.
Анонс - https://community.letsencrypt.org/t/acme-v2-and-wildcard-certificate-support-is-live/55579
Обратите внимание: "wildcard domains must be validated using the DNS-01 challenge type. This means that you’ll need to modify DNS TXT records in order to demonstrate control over a domain for the purpose of obtaining a wildcard certificate."
Поддерживаемые платформы и ПО - https://letsencrypt.org/docs/certificate-compatibility/
Библиотеки для go, java, node.js, perl, php, python, ruby, powershell -
https://letsencrypt.org/docs/client-options/#acme-v2-compatible-clients Найдете на любой вкус и цвет.