what drives compatibility of new hardware

[milomak]

what is it that makes a device compatible with the latest macos offering?

 

[Jamesbond007]

what is it that makes a device compatible with the latest macos offering?

What devices are you referring to?

If you are talking about graphics cards, for example, then the important thing is whether MacOS includes drivers for them. So, current Nvidia graphics cards (GTX 10xx / GTX 16xx / RTX 20xx) are not supported as MacOS does not include drivers for them and Nvidia does not offer drivers either. AMD graphics cards like the RX 5x00 series are supported on MacOS Catalina 10.15.2 and later as the necessary drivers are included in MacOS Catalina.

The same applies to older graphics cards. My RX 580, for example, is supported on MacOS Sierra 10.12.6 and later as the necessary drivers are included starting from MacOS Sierra 10.12.6.