This may also work for 64 bit Gimp-2.8 as Gimp-2.8 can use a 32 bit executable.
For 64 bit you may need to place the executable stand alone in the 32 bit program directory first.
The zip is attached with directions, and credits in the README-PLEASE file.
The python module opens the stand alone. Tools>GIF2APNG - This opens a manager like Shellout.
Just select ok and the program opens...
The stand alone allows you to browse for your GIF and then after selecting convert will convert it to APNG.
Why use it in Gimp if it's a stand alone?
Cause i am lazy - And you can create a GIF and export it then open the GIF2APNG program and convert it all the while keeping Gimp open.

IF you have the APNG plugin installed you may then open the apng file in Gimp after creating it.


Other downloads
https://sourceforge.net/projects/gif2apng/files/1.7/
Enjoy!