What OSes besides Windows, macOS, Linux, Solaris, AIX, HP-UX, z/OS, mobile (Andriod, iOS)? SCADA stuff perhaps?
And how many of those operating systems are targeted by worms and ransomware?
I know when I used to admin Solaris and IRIX machines we were worried a lot less about attacks than the Windows desktop folks. An nmap of the systems showed SSH open and one or two other services, which meant very few vectors for attack.
The fact of the matter is that by securing desktops, one probably takes care of 80% of a company's attack surface. Next take care of your Windows servers, which is another 10%. Then go after Unix-y servers and things like printers, HVAC, IPMI, etc (which should be VLANed off).