Given the size of some Electron software, bundling TCL/Tk with IronTCL and TCLLib+TKLib weights 58MB and you can develop your own software with it, and that with the source of everything included.

And if you set a native theme for TTK in your code (literal two lines), your software will stop looking Motif-Industrial, the widgets will have the classic Win32 themes. It will look native from XP and up.