The Windows version just assumes 7z is installed

[bopt-woba]

The Windows version has a silent dependency on a 7z installation. There is no way around the default discovery mechanism, which only looks in the registry and the program files directory.

• I cannot use a custom path
• 7z will not be looked up in %PATH%
• 7z is not necessary at all

The funny thing is, that tar is available on any Windows starting with Windows 10 build 17063 (December 2017), so just using that would be easier. Windows systems before that should not be used anymore anyway.

So please use tar (includes automatic .gz decompression), which should reduce the code complexity while removing gratuitous dependencies. There is no need for custom software installations on Windows. The following will suffice:

mkdir tzdata
tar xf tzdata2025b.tar.gz -C tzdata