There is only one file type that uses the .OGGSTR extension:
Godot Engine Ogg Audio File
An OGGSTR file is an audio file created by Godot Engine, a free and open source game engine used to create 2D and 3D games. It stores audio in a format similar to an .OGG file, which is compressed with Ogg Vorbis audio compression but includes a custom header. OGGSTR files are created when a user imports an OGG file to be used in a game for sound effects, background music, or narration.
Updated: November 1, 2019