Just released Beta 15 of the Catalina PartialPatcher utility, which now includes a (basic) post-installation tool! Just boot off the installer volume a second time after completing your Catalina installation, and run the tool from the Utilities menu.
Nice. Out of curiosity, how far away are you from being able to get rid of the nvram boot-args="-no_compat_check" requirement? Is that just a matter of finding all of the platform checks or has something more significant changed in Catalina that requires this?