Macs come with an Apple provided antivirus built in, it's called XProtect.
Apple also has enforced a similar policy to what Google is doing, but much stricter, and has done for ~13 years or so (devs must be identified, the OS rejects unsigned code in all territories by default, Apple pre-approves all binaries even outside the app store).
Linux distros have policies far more extreme than anything Google, Apple or Microsoft have ever done. They explicitly don't support installing any software not provided by their "app stores". Getting into those requires giving up your source code to them, and they reserve the right to modify it as they see fit without informing anyone, reject it for any reason or no reason at all (including reasons like "we don't have time"), and they tie getting new releases of your app to the user upgrading to new releases of the OS. If you do try and install stuff from outside of your distribution, not only are there security warnings to click through but an expected outcome is that the OS breaks and the vendor washes their hands of you.
Despite those policies, or perhaps because of them, botnets of Linux servers are common.
Of all consumer-facing platforms only Windows and Android allow installation of unsigned third party code out of the box via some obvious graphical path. And on Windows that right is somewhat theoretical. You can do it but the built in browser will try very hard to stop you, and the OS itself will happily break unsigned code by blocking file open syscalls heuristically. So in practice most apps don't go the unsigned route. On Android OTOH, unsigned (non ID verified) code is sandboxed and works just like regular apps after installation, the OS won't heuristically interfere with the app.