One of my favorite apps on macOS, Ice, stopped working when I updated to macOS 27 because the trick it relied on doesn't work anymore. The only thing I really needed from the app was the ability to hide menu bar items to the left of it, so I built Chest to do just that.
There are other apps like this as well that try to use the menu bar part of macOS's exam mode to hide items, but that approach has some issues with the screen sharing, microphone, and camera indicators in the menu bar, which is rather troublesome for me.
Chest works by emulating the "Allow in the Menu Bar" switches in System Settings rather than relying on the old trick of pushing menu bar items off-screen.
It just needs Accessibility permission and access to two files that let it control which items are shown in the menu bar and where they're placed.
You can hide items in two ways: by ⌘-dragging them to the left of a small dot in the menu bar, or by dropping them into a separate "Chest" that keeps them out of the menu bar entirely. Clicking the dot brings the hidden items back.
I think our approach is rather cleaner, and the app itself sits at ~2 MB, so it's small enough to not matter while providing a clutter-free menu bar.
You can view the source at https://github.com/boringbar/chest