So do CAs in general offer those? Are they as affordable as "normal" certs? Certainly you need to be paying for that those kind of certificates, possibly some premium?
It's probably not worth it anyway, because you're now stuck with that single IP, for little benefit. In general IPs just don't get HTTPS certificates acquired for them.
Seems to be free from ZeroSSL https://help.zerossl.com/hc/en-us/articles/360060119973-Is-I... but Letsencrypt decided against it since their whole thing is about proving ownership over a domain, or set of domains, and doing that for an IP address would be some nonsense. I would be absolutely shocked if the "name brand" cert issuers don't support CSRs containing iPAddress SAN entries, since it's very clearly part of the RFC, but I haven't ever had a need to try such a stunt, either
It's probably not worth it anyway, because you're now stuck with that single IP, for little benefit. In general IPs just don't get HTTPS certificates acquired for them.