Google has pulled the Local Home SDK out of beta. Developers can use it to develop small Assistant apps that can communicate with compatible smart devices in the home, without the command going through the Google cloud first. That should go faster.
However, if a local action does not reach its intended target, Assistant falls back to the cloud to try to transfer the command after all. Devices can be discovered over the local network via mdns, udp and upnp, and applications must be written in JavaScript, Google writes.
Local Home Control was announced at Google I/O in 2019 and has been available in developer preview ever since. Google now considers the software mature enough to be released to the general public. Google speaks of the possibility to control ‘local smart devices’, but does not give any further details about what exactly can be controlled. It is plausible that at least smart home hardware fits into this picture.