Unable to update my MacBook Air M1 from macOS 15.2 to 15.4

Just to add to the already good advise from @ Servant of Cats

The installer needs a stable internet connection to download macOS and get firmware and other information specific to your Mac model. Make sure that your Mac is connected to the internet.

refer >> If an error occurred while updating or installing macOS - Apple Support

You should try to run First Aid on Disk Utility.

If this don't work, download Sequoia on another Mac or download a Sequoia installer from the internet (I personally don't recommend trying download it from the internet, because the source can be insecure) and make a bootable drive (like a pen): Create a bootable installer for macOS - Apple Support, and try installing it through that bootable external drive.

You can also reinstall macOS (the most recent version available) through macOS recovery (see the instructions to Apple Silicon Macs) How to start up from macOS Recovery - Apple Support.

If none of this work, consider doing a Time Machine backup and erasing the Mac.

Hopefully this is not the issue, but just in case it is …

TidBITS – Solving the macOS Installer’s “Failed to Personalize” Error with New Firmware

The article also mentions some other ways of trying to fix the problem that do not depend on having access to a second Mac with the Apple Configurator tool (or taking your Mac to an Apple Store or service provider).