They are, but I would only use one as a second device besides a real Mac. Setup and updates are relatively painless if you choose the right hardware and store a

They are, but I would only use one as a second device besides a real Mac. Setup and updates are relatively painless if you choose the right hardware and store additional kexts not on the system OS partition but the EFI boot partition. Biggest troubles are WIFI and Bluetooth (and therefore continuity, needs one of a few selected cards), graphics (no nVidia) and keyboard and trackpad (for desktops, use used Apple peripherals) as well as sound in some configurations (might use a Bluetooth speaker if BT works). It always can happen that you mess up (or need access to a real Mac for downloading the OS in the first place), so have a Backup and wait a few days after system updates appear, read forums about possible showstoppers and necessary precautions. That said, Catalina is still not perfect and troubles may not be caused by the hackintosh but the OS.