I bought exactly this trip potty in the US and I have to say it was the best purchase ever. It fits in just about any bag and is therefore always ready. Especially if you are still in potty training, and the infant must pee now, it's convenient. For it is no longer dependent on public Toitellen.
It can be used as toilet seat, or as a stand-alone potty with or without bag (there are a couple with supplied) be used. I just go with the diaper bag of Rossmann, is much cheaper than the original nachzukaufen. Is a clean affair. Outdoors, you can use the potty without bag.