Can I use Crosshair X in Rust?

In short, the answer is yes. Facepunch has not made any statements against the use of crosshair overlays.

Crosshair X and EAC:

Crosshair X is EAC compliant because it runs completely independently of any game process. The fullscreen overlay is achieved by using the Xbox Game Bar on Windows 10 which is a trusted overlay platform built by Microsoft. This allows Crosshair X to run completely independently of any game and process, making it secure and anti-cheat compliant.

How to Set Up

Make sure your version of Windows 10, the Microsoft Store app, and the Xbox Game Bar are fully up to date.
Download the app from either Steam or the Microsoft Store (Free trial)
Setup the Game Bar Extension by following the in app tutorial under the ‘Exclusive Fullscreen’ tab.
Choose your favorite design or make your own. Any design you select will automatically import to the designer so that you can adjust it to your liking.