Is it possible to build an extension for safari?

[jackyspeed]

Hi, I have been using this extension for years and grow deep dependence on it on edge. Recently, I moved to Safari, and Safari provides a functionality to save a whole page into a single file, but in a format that other browsers cannot read. It is not a good way to preserve a page offline for long term use, since you can never know you will use safari forever. It would be very nice if safari has this SingleFile extension. Is it possible to port this extension for safari extension? Thanks!