Thanks, this answers for point 1, But for point 2, will fly charge 0.10/month as Single hostname certificates if i use custom domains. Im planning to point 1000+ custom domains that is why having this concern.
They don’t care how many domains you connect. What they care is how many SSL certs you deploy. Which means, if ALL of you domains can run under the same wildcard cert, then you’ll only be charged $1. If not, you’ll have to pay for each cert
You need to think about how requests come in and where they go, then it becomes pretty clear:
if you “get and add certificates for each subdomain” you will get charged $0.10/month for each subdomain since you are getting a different, non-wildcard certificate for each host
If you “get and add one wildcard certificate for *.site.xyz.ai” and only use that one you will get charged $1/month, since you are getting 1 wildcard certificate in total
For your use case, if you want to use one wildcard cert for everything, you need to either put a proxy in front of everything and terminate SSL there or possibly use Fly-Replay