Universal Control is mostly but not entirely reliable—and you can’t use it to log in to a Mac.
If you’re in the unique situation of needing to use two Macs at once, the task can be made easier if you can control both of them with one keyboard. Here are a couple of ways to do it.Universal Control
Universal Control lets you share a mouse and keyboard across multiple Macs and iPads that are in proximity and logged in to the same Apple ID account. It has its limits:
You need the correct Macs (running macOS Monterey version 12.4 or later) and iPads (iPadOS 15.4 or later); click the link above for minimum models.
Your Mac has to be logged in, as Universal Control relies on Continuity’s Handoff feature, which only works while an account is active.