You can simply repack TGZ archives to basic ZIP with file archives that supports both formats, which means mostly all of the currently available.
Convert Gzip compressed TAR archive to WinZIP Compressed ZIP archive.
We found 9 software records in the database related to .tgz to .zip file format conversion.
Microsoft Windows software - convert tgz to zip on Windows
Another popular file archiver and compressor
Convert from tgz file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned tgz to zip. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
One of the oldest and most popular shareware file archiver and data compression utility
One of the many available file compression utilities
A free open source archive utility
An archive opener for Microsoft Windows and Mac OS X
Apple macOS / Mac OS X software - convert tgz to zip on OS X
Mac version of a free file archiver
Mac version of the popular utility
A backup and archive utility
Linux/Unix software - convert tgz to zip on Linux
A Linux application used as frontend for popular compression tools