Convert APK to WGT

A WGT file extension is related to a widget package used by Tizen-based devices. Tizen is an open-source software platform supported by several devices, including TVs, smartphones, TVs, wearables, etc.. Users mostly search for a guide on "How to convert Android to Tizen" or "How to convert Android apps to Tizen". Opera browser also uses WGT file suffix for its widgets. 

You can't directly convert Android Packages to Tizen or Opera Widgets using some APK to WGT converter, as these are two different file types and/or operating systems.

Instructions for a possible workaround to convert Android to Tizen:

Tools like the APKTool will let you decompile your application and extract the code source. You will need to analyze the code and understand the application's structure, logic, and features. Study the application's interface and functionality to become familiar with it.

With Tizen Studio, the official IDE for Tizen app development, you can recreate the app according to the original Android code. While programs and libraries particular to Android must be updated, others, including HTML and CSS code, may often be used as-is.

Please be aware that this can be a difficult task and that experience in Tizen App development is required, depending on your application's complexity. 

Simply put, it is impossible to convert APK to WGT directly.
Thus, there is no so-called apk to wgt converter or a free online apk to wgt converter to be found.