These UWB chips claim to do "X meters away in Y direction". The direction aspect could be revolutionary if it works well. AirTags is the perfect use for it as well.
If the sound is muffled and you can’t hear it, this sounds like it could narrow it down to a specific room or maybe even area of a room. Which is a huge improvement.
I haven’t personally used a Tile before, but my impression was “you get what building it’s in, then have to search everywhere til it’s in earshot”
So Apple's +-30cm does seem to be a fairly major improvement, if true.
Overall, If you have a UWB receiver devices installed ~ every 4-5 meters (15 feet) you can triangulate beacon's position to a pretty precise degree (around 10 cm / 4 inches accuracy). You can even detect the height of a beacon above the floor.
However, triangulation is the key. Often we have to install extra receivers just to deal with big columns and barriers, sources of intense electromagnetism (like big electric engines or microwaves), or some materials (glass doors turned out to be a major problem, wooden doors - not so much).
I'm not sure how accurate a positioning can be with your phone acting as a sole UWB receiver. Clearly Apple can make it work sufficiently well for an everyday use, but it won't be as precise as they show in carefully constructed demos.
two antennas using time of flight to achieve angle of arrival