Is this the case? How does that work? Genuinely curious. I remember I had macOS (Mac OS X, actually) on my PC. My last Hackintosh was Mac OS X Leopard. Everything seemed to work well... back then. I even had XCode working.
iMessage can be made to work with a hackintosh. You just have to go the whole way in making your hackintosh fully Mac-like with a fake but plausible/realistic serial number and expected network setup. You can’t stop at just getting macOS installed and booting.
I’ve had multiple installs in the past where it worked fine.
While it’s ultimately up to the person doing the hackintoshing and thus an “honor system” thing, all the guides are pretty explicit about how you should generate serial numbers that are syntactically valid but cannot belong to real machines, for example that of a 12” Macbook manufactured in 2020 in Cork, Ireland (no such machine exists, as they were discontinued in 2019 and manufactured in China). That way there’s a small chance of collision with other hackintoshers, but no threat of accidentally using the serial of someone’s real Mac.