@MLVC
In theory you can´t do this but according to Apple you also can´t invite people to your home if your hubs/homepods and main IOS devices are on IOS 16 and the ones you want to invite to be part of your home are on IOS 15, but I just did that a few weeks ago with a couple of family members and their Iphone 7 (which dont support IOS 16).
They are now part of my home, control accesories, and have personal requests. They accepted the invitation and everything went smoothly.
Everything in my house is on 16.1 and can be upgraded to 16.2... except for these two devices.
In theory, that means that I am not going to be able to upgrade to the new architecture when 16.2 gets released, because these old devices will be kicked out permamently from the home app.
But we´ll see. Apple could even release a 15.8 update with support for the new architecture, but I highly doubt it.