The HomePod Mini brings a long-awaited first to HomeKit: compatibility with “Thread” connectivity, which allows the accessories themselves to communicate with each other to forget about bridges and repeaters.
Creating your network of HomeKit-compatible devices requires an "Accessory Central" as an essential element. All HomeKit devices must be connected to it, either via WiFi or via Bluetooth, for them to work properly and run all automations, to be able to access remotely from anywhere in the world, etc. When the connection to the control panel is via WiFi, there are no major problems, but When connected via Bluetooth, with a much more limited range, this connection to the control panel is sometimes impossible and that's when you have to add another accessory center, or a bridge or repeater.
With the arrival of the HomePod Mini, this problem will be solved to a large extent, since the small Apple speaker is compatible with the “Thread” connectivity, which by making use of low-consumption Bluetooth, allows the accessories themselves to communicate with each other. Yes, establishing a MESH network that allows everyone to be connected to the central, even if not directly. For example, if you have a garden irrigation controller that can't connect to the Apple TV in the living room, it will connect to the smart plug in the hallway, which is connected to the Apple TV.
This type of connectivity makes use of Bluetooth, so most accessories on the market can use it with a simple firmware update. Eve, one of the most important manufacturers of HomeKit accessories, has already announced that its devices will be made compatible over the next few days through updates that will appear in its Eve application for HomeKit (link), and Nanoleaf has already announced its upcoming Thread-compatible products.
And this is just the beginning, because "Thread"is the result of work within the CHIP Project, in which Apple, Google, Amazon and Zigbee participate to achieve a universal standard that allows compatibility between all home automation products, regardless of brand or platform. Remember, to be able to use this “Thread” connectivity, it is necessary to have a HomePod Mini as an accessory center, the normal HomePod does not allow it.