On Apple Developer pages under "Nearby Interaction" section there is a list of recommended UWB Chipset Manufacturers: https://developer.apple.com/nearby-interaction/ You can also google "UWB Beacons" and get one of the available Developer Kits. They typically have the latest UWB chip that is compatible with FiRa and interoperable with U1. After you test their Dev Kit you can contact the company and they might provide additional services if you need to design own tags, etc.

With iOS15 it is possible to range and get both distance and angle orientation between U1-enabled Apple device and UWB-enabled third-party device that is compatible with FiRa and interoperable with U1. You can use Nearby Interaction API for this - more details here: https://developer.apple.com/nearby-interaction/ If you want to build an iOS app that is ranging with 3rd-party UWB devices just google "UWB beacons" and get one of the available Dev Kits; they typically come with SDK including sample code, so it's trivial to integrate it to your mobile app.

In general UWB devices can range even being 30-50m apart. However that really depends if this is line-of-sight situation and also how big is the antenna/antennas and its orientation. E.g. signal that is going over human body/wall might be weaker. Note also that U1<>U1 or U1<>UWB interaction is done typically over both BLE&UWB where the initial "hand-shake" is over BLE because this is lower-power. BLE is typically more sensitive to obstacles/orientation. Finally, it seems Apple wanted U1 to be used for "NEARBY Interactions", so perhaps that is their design choice to optimize only for objects that are around, perhaps within human-eye visible range, thus range might be limited artificially as well.