Is it ok to use a 4TB seagate skyhawk hard drive for this use case? I heard that it has a lower read speed versus the ironwolf or traditional hard drives, since it is designed for 24/7 writing. Is it really that detrimental for my specific use case? Or is it not what they say it is? Considering buying a skyhawk because I can get one cheaper than the ironwolf version. Thank you!
Correct, it won't perform quite as well as the Ironwolf but the difference is likely in the eye of the user. For NAS use you're probably fine with either. When you start talking "hypervisor" though, it completely depends how many VMs we're talking about, what kind of performance you want out of them, etc.
Are you putting them in to a RAID array in an actual NAS?
I will be using proxmox, at best I'll spin up 5 containers and 1 KVM. I won't be raiding it though, my mini ITX mobo only has 2 SATA ports and I already have a 1TB HGST hard drive with movies on it formatted to EXT4. So I get to use the last port for this seeing that my 2TB WD failed just recently and hoping to replace it with a 4TB skyhawk I found on the FB marketplace, sealed and brand new, and cheaper. Will I see a noticeable difference?