Google does not support local control like Amazon’s Echo Dot’s generally do. That’s how WLED gets Alexa to work locally without paying for or subscribing to an online service, by emulating a device that Echo devices can recognize on the local network, and then control locally without an outside service.
It is not because of lack of interest. Rather, it is lack of funds to pay for such a required service when only a relatively small percent of WLED users want / need GA/GH integration. Of those few, how many are also willing to pay for the required server / fees or subscription fees? Probably far too few to make it worthwhile.
The link I provided is one person’s work-around using an online service, IFTTT, to be the go-between that has already paid the fees necessary to be a part of the Google Home infrastructure.
I appreciate that there may have been financial issues which is why I suggested piggybacking on top of the existing Magic Home Pro protocol. Those devices are already well supported by Google Home and are very similar in purpose.
On the topic of costs, I have been unable to find any references to costs. The information at Overview | Actions on Google Smart Home | Google Developers doesn’t hint at costs for adding services. All they seem to require is an authentication server to validate users of the actions you create. (I did not investigate this in any detail so there may be costs which I didn’t find or note.)
Authentication server
Not free. Requires money to: purchase server & domain name, plus time to configure and maintain.
The reverse engineering of the protocol only allows a computing device on the same network to control a MHP based device. It does not make it behave as if it were controlled from GA/GH. It is a no-win scenario to look in that direction - unfortunately.