HiraokaHyperTools.LibEditRegistryPol

This will provide reader and writer for Registry.pol file format: Registry Policy File Format | Microsoft Learn

Links: Doxygen

Reader sample

var bytes = File.ReadAllBytes(@"C:\Windows\System32\GroupPolicy\Machine\Registry.pol");
RegistryPolEntry[] entries = RegistryPol.Read(bytes).ToArray();

Writer sample

ReadOnlyMemory<byte> written = RegistryPol.Write(new RegistryPolEntry[0]);
byte[] bytes = written.ToArray();