Can we modify macOS 26 BaseSystem.dmg to emulate a native macOS 27 installer experience on Intel?

Hi everyone,

As we all know, Apple has completely dropped Intel support in the latest macOS versions. However, I want to pitch a highly technical workaround for system modders and deployment experts here. [1]

Instead of messing with post-install setups, what if we target the installation source itself? Is it technically possible to unpack, modify, and repack the core BaseSystem.dmg of macOS 26 (Tahoe) to mimic the entire identity of macOS 27 (Golden Gate) right from the boot/recovery phase? [1]

The core approach would involve making the image writable, mounting it, and executing the following tweaks inside the macOS 26 skeleton: [1, 2]

1. System Identity Overhaul: Modify all system version strings, plists, and system metadata inside the installer image to rename the OS from version 26 to version 27.
2. Asset Substitution: Replace the default installer backgrounds, icons, and menus with the new macOS 27 Liquid Glass assets.
3. UI Transparency Tweak: Inject front-end asset overrides inside the recovery framework to simulate the high-transparency Liquid Glass environment during setup.

By keeping the core kernel and kext stack of version 26 intact, we preserve 100% Intel compatibility for hardware like Dell, ThinkPad, etc. Yet, the moment the machine boots into the installer, the user is greeted by a seamless macOS 27 setup screen. Upon a successful installation, it would ideally boot directly into our pre-customized macOS 27 interface rather than a stock macOS 26 desktop. [1, 2, 3]

Has anyone experimented with deep image modifications of BaseSystem.dmg on recent macOS versions? What are the main roadblocks regarding code signing (SIP/SSV) or checksum verifications (BaseSystem.chunklist) when modifying the recovery base image like this? [1, 2]

I would love to hear your insights!