For the past couple of weeks, I've been playing with getting a VM working on ArcoLinux while, in parallel, working on problems in Proxmox. I did this to check on 2 issues: getting Thunderbolt to work and getting rid of the USB dropout problem.
The potential advantage of ArcoLinux, unlike Proxmox or UnRAID, is that it gets the latest kernels; maybe a year or two faster than Proxmox or UnRaid. I've finally got a Catalina VM working (see image below). However, I've not yet passed the GPUs and I'm presently only passing 8 cores to the macOS VM.
While the installation of ArcoLinux is simple and not much different than Proxmox, setting up a VM is more involved. In ArcoLinux, there is more support for VirtualBox (which doesn't seem to want to play nicely with macOS), but Virt-Manager seems to be a more flexible choice. However, it takes a few more steps to get it working. (I did not document what is involved, nor do I plan on presenting a tutorial; this post is more of an FYI.)
Once Virt-Manager is installed and the usual vfio files are created (same as with Proxmox), running the VM is straightforward. There are a few differences, such as the devices seen with IORegistryExplorer having different addresses, which appear more ordered. (I'll later update an image or two to this post.)
As with Proxmox, I was not able to get Thunderbolt working for the same reasons: no ability as of yet to pass the bridge portions. Although, I thought I'd read that in the near future, the Linux kernel will allow passing whole devices. (And since ArcoLinux kernels seem, a VM running under ArcoLinux might be expected to pass TB before other distros.)
With regards to the USB audio dropout problem, it is about the same as with Proxmox. However, I was able to noticeably reduce, if not eliminate, the dropout by turning off BT and WiFi. (I tried this once before in Proxmox and did not notice an improvement; but I'll revisit it again.)
Catalina VM under AcroLinux: