So I'm running VirtualBox, not MP5,1, but VirtualBox has the restrictions of no AVX or no AVX2 that MP5,1 does. TLDR version, I can report 15.0.1 runs fine on it. But the CryptexFixup (no AVX2) patch probably means OTA *won't* work (it didn't used to), you'll probably have to download full 15.0.1 installer and install that.
I prepared my VirtualBox (which had been running 14.7) with OCLP 2.0.2 etc. intending to update to 15.0. Took a little fidding to get it to boot into 14.7 to begin with (I tell it I had a MacBookPro10,2 since that has everything working but ethernet and "no AVX" support). Add ethernet driver (AppleIntel8254XEthernet -- I have no idea if the IntelMAUSI would work, I didn't try it since this one works). And add the "no AVX" patches from MacPro 5,1 OCLP settings (NoAVXFSCompressionTypeZlib-AVXpel and NoAVXFSCompressionTypeZlib). And I turned on keyboard input on the boot screen, and set resolution (since the default "max" -- since VirtualBox doesn't have a physical monitor -- picks something ridiculus like 8K or 16K resolution or something). (My physical CPU now does have AVX and AVX2 -- I'm on a Coffee Lake... although I previously did use a Ivy Bridge with no AVX2 setting this up. But in VirtualBox, AVX and AVX2 don't pass through without "Nested Paging" being turned on, and macOS doesn't boot with Nested Paging. So no AVX or AVX2 in VirtualBox with macOS.)
So 15.0.1 came out in the interim so I updated to that instead. You have to use the InstallAssistant.pkg (download the full 15.0.1 installer), OTA updates don't work with CryptexFixup (no AVX2) patch, but it installed and ran fine. (The more minor software updates, like where it downloads a newer Safari or etc., work fine -- just not when it goes to a newer version of macOS. Unless OCLP 2.0.2 setup changed something so OTA does now work on these models that need CryptexFixup. It didn't work in the past and "no OTA with CryptexFixup" was documented in the past, but I dind't actually try OTA this time to check if they'd changed that.)