Only if you already have the ability to read arbitrary RAM. So running in kernel/hypervisor mode.

The exploit is being able to do it from usermode through an api (browser/js) that normally forbids that.

Userspace can only access its own memory, rather than the whole systems.

Userspace processes can only read their own memory, or what has been shared with them.

so how do programs like Cheat Engine and WeMod work, on windows? they don't request an administrator password, and i can tamper with any processes' memory i've tried, including firefox.exe and the like.

https://cheatengine.org/

https://www.wemod.com/