For that, my plugin Post-Export Command can be helpful. See the following thread for usage guidance:
https://forum.glyphsapp.com/t/what-is-the-best-way-to-add-a-binary-table-to-exported-font/19392/6
(The plugin is not yet in the Plugin Manager, add https://florianpircher.com/glyphs/packages-preview.plist to Glyphs → Preferences… → Addons → Alternate Plugin Repos. That puts the prerelease version in the Plugin Manager for download.)
But Glyphs-file-specific export is important enough to either be added as a feature to Glyphs directly or as a separate plugin.