I envolved in a similar project like your situation some years ago. They designed to set up the vCenter VM as a Hyper-V and they vindicated their plan like this, if the ESXi hosts failed, they have still access to the vCenter server. I convinced them it's absolutely wrong! because of the following reasons:
1. VMware has many Availability features and technologies (like HA & DRS) to keep the services up and running against many types of disaster/failure. So naturally, it can protect its primary management service (vCenter) too
2. After the release of vSphere 6.5, VMware introduced a very impressive feature for vCenter availability, called VCHA (vCenter High availability). Although it needs to deploy three VMs, Primary VCSA, Passive, and Witness into the three different hosts (you mentioned sadly there exist only 2 physical hosts in your network environment)
3. Using two different platforms of virtualization is not a good design and is not recommended! There is no benefit in these types of design. Using one single platform is the better option and there is more integration.
So I strongly recommend that convert the VM inside the Hyper-V host to the ESXi host and then clean the server and install the 3rd ESXi host and use to in your virtual infrastructure. Regardless of what you do about the 3rd physical server, you can deploy the VCSA (certainly use the appliance mode, not the windows-based) without worry, and remember if you even lose it temporarily, the ESXi hosts and their VMs working correctly.