Want to be able to DIN rail mount a QO-GFI breaker instead of panel mounting.
No there is no QOU-GFI version available. Suggested alternative is a QO-GFI breaker and an OEM mounting base such as the QON2L40 for 1P and 2P QO-GFI breakers or QON403L60N for 3P QO-GFI breakers. These bases are NOT DIN rail mountable but they are an alternative to a large panel interior. They are found on Digest 177 page 7-16.