It can stand for whatever it likes, emulation has a colloquial meaning.

What? It's not talking about WINE, it's talking about SteamOS.

> The Steam Machine is basically a tiny gaming desktop for your TV, running the Steam Deck's SteamOS. That platform is a Linux distribution optimized for emulating Windows titles.

SteamOS uses Proton for Windows compatibility, Proton is a fork of Wine, Wine Is Not an Emulator.

Ah, that's my bad.