Because these are modified versions of copyrighted software, you won't find them on official Microsoft sites. They are typically hosted on:
Before you look for that .zip or .iso file, remember that "Ultralight" means things are missing: Download Windows Ultralight (22621 590) FBConan zip
Often used as a mirror for older, stable builds. How to Install Safely If you decide to try it, follow these "Pro" steps: Because these are modified versions of copyrighted software,
If the uploader provided MD5 or SHA-1 hashes, check your download against them to ensure the file wasn't tampered with. These ISOs usually bypass TPM 2
These ISOs usually bypass TPM 2.0 and Secure Boot requirements, making them popular for older hardware. The Trade-offs: Is it Right for You?
The primary forums for custom Windows builders.
Test the ISO in VirtualBox or VMware to see if your essential apps even run.