One way I hope Kommit can add value, is that it doesn't require your commitment to be digital and there doesn't need to be an API integration (Beeminder is primarily based on API integrations). If you can prove your commitment with an image, video or text, your good to go. The downside is that nothing is automatic.

Update: You can manually enter data into Beeminder, therefore it can also handle non-digital commitments. However, as far as I am aware, the manually entered data is not verified (e.g. by having it checked by a reviewer) hence I didn't feel like it was their focus.