I used dehydrated for a while. It's a quite simple python script iirc. It's on github someplace.
If your domain registrar is porkbun and you use their DNS hosting, they can generate wildcard certificates for you. It is pretty convenient though a little bit scary, since they generate your key pair and retrieve the cert from letsencrypt. But, since they run your DNS, they could do almost the same thing without you even knowing.