You can use your PIV-enabled YubiKey on a variety of platforms.
Windows has built-in PIV support. You can use it for logging in to an Active Directory connected machine, to encrypt files using BitLocker, to sign executables using signtool.exe, etc. For more information, see: https://technet.microsoft.com/en-us/library/ee706526(v=ws.10).aspx
Linux and macOS support PIV by using the tools provided by the OpenSC project.
This enables you to sign software, to authenticate over SSH, and so on.
Apple devices running iOS 14 or newer support PIV when using the Yubico Authenticator for iOS app to interact with a PIV-enabled YubiKey for certificate-based authentication in Safari browser, email signatures and encryption in the native iOS Mail App, and so on.