What hardware you will need to launch your AR experience depends on the purpose and the complexity of that experience.
If you’re interested in a retail, marketing, product demo, or even educational augmented reality application, you and your consumers won’t need anything more than a mobile device! The beauty of AR experiences is that all you have to do is download an AR app (or access an experience via the web), and you can enjoy it on your phone or tablet. Make sure that it is an AR-ready phone or tablet, however, because not all are.
If you want AR technology for training or advanced work in construction, design, repair, or similar, perhaps it would be better to go for an AR headset or glasses (or a mixed reality headset), such as the aforementioned Microsoft Hololens 2. There are plenty of other options out there (Google Glass Enterprise 2 and Lenovo ThinkReality A6 come to mind). Even Apple has announced their very own AR glasses coming in the next few years!