I will respond here, since some arguments of all are pretty similar.
1- "The security of dom0 doesn't matter"
I don't agree with that. The Qubes OS depends so much in the security of Xen. If Xen gets compromised, then it's over. Qubes OS does not offer additional protection against vm escapes. That's why i don't understand what's the difference between running Xen on Qubes vs. your OS of choice.
"But dom0 has no internet access. They have a dedicated vm for usb, network, etc." That's don't justify. The fact that dom0 has no internet access, is good to protect you from attacks directly to dom0, trying to "skip" the need to do a vm escape and land on your VMs. That just does not protect you against a compromised vm/vm escapes. You could create a dedicated vm for usb and network with another hypervisor, another environment. Very easily too.
Using some better base for dom0, like Fedora Silver Blue or Secure Blue, would add more security features and more stability to the system. 2 important things in a environment where security is the top priority.
2- "Dom0 doesn't have internet access"
Again, that's doesn't matter. If Xen gets compromised, the fact that dom0 has no access to the internet would not reduce the impact of the attack.
I'm talking strictly about security here. In that sense, Hyper-V is, arguably, more secure than Xen, since Hyper-V had far fewer CVEs and vulnerability's than Xen (Even Xen on Qubes OS have more CVEs and vulnerabilities documented than Hyper-V, just look at QSB's.). If an attacker could compromise the Hyper-V and realize a VM escape, he will have a hardened Windows, which contains many advanced security features that could, in theory, reduce the impact of the attack, such as UWF, which turns the entire Windows environment in a read-only system, immutable. Firmware and Kernel protection, and so on. With Qubes OS, the attacker would land in a dom0 with a old version of Fedora and many old/vulnerable packages. Even the sys* vms are insecure, since they all are based, as default, in debian-12-xfce or Fedora-41-xfce. You could use OpenBSD as sys-net, but that's not officially supported and is pretty buggy. And since that requires a loop with the sys-firewall, we don't know exacly if that really cause gains of security. What i trying to say is: Qubes OS's security really makes that difference to justify its use? Because Qubes OS is a system very, very limited. The hardware specs are high. The desktop experience is limited. No 3D aceleration, complex to use, etc. Qubes OS is unusable almost like OpenBSD for Desktop. I don't think the difference between security of Qubes OS vs Windows is high to justify the use of Qubes. I really don't know people, even the one's that care much about security, that use Qubes OS or recommend his use. The unique that i saw is Edward Snowden. Even people that are in a dangerous situations, like malware analysis, red team, don't rely on Qubes OS. Why? 90% of the users base of Qubes OS are just paranoid people with no actual knowledge on how security works.
Also, another thing that i would like to add: It's important to notice that Qubes OS is not suitable for anonymity and privacy, even if some people use him with this purpose in mind. The fingerprinting of the VMs are high. The NetVM scheme exposes detailed information about your network use in your local network and to your ISP. While Whonix is trying hard to mitigate that, he is not succeeding very well in that. So, if someone says that he uses Qubes OS because it's open source and cause they prioritize anonymity, then he is using it for the wrong reason, i guess. Many Qubes OS developers already said that they focus was never privacy nor anonymity. We have inumerous problems of anonymity and privacy. The fingerprint of Qubes OS is high. The use of Qubes OS is obviously. We have Fedora Phone Home, Qubes having all information of your hardware, some codes of Qubes OS that's not Open Source (yes, Qubes OS is not fully open source and they say this on their docs) and so on.