Whichever PowerPC computer was the last one Apple released. (Then you can use Tiger + Classic Environment).

But, you could also use Mini vMac, which is a very capable emulator.

There are also turn-key OS7 and OS9 apps that can be run under Catalina with minimal fuss

For that matter, qemu can emulate a powermac.

^ It can, but I've found it to be not particularly pleasant to use. Lots of weirdness, particularly around input. It may have been my setup, but still.

Mini vMac by contrast is quick, pleasant, and plug n' plug. (It's also emulating a completely different era of course, but it's enough for hypercard.)