New app — which CUSTOM DTH’s will work?

Every device except for mobile presence will show up in the new app. Whether it will automatically work or not is the big question. Some of mine such as Xiaomi contact and motion worked automatically. Others I’ve recently gotten working myself. I suspect at or before Samsung Developers Conference in November they will publish documentation of how to get custom handlers working. In the mean time, if you want to do some tinkering, go to their public GitHub and search for mnmn and vid entries in the metadata definition. Add the same to your custom handlers and edit and save the device to test.