How can I fix "Unable to Complete Home Update"

When trying to update the architecture of my current Apple Home, I'm encountering the following "Unable to Complete Home Update" error.

I've tried several different things to try and solve the problem such as:

• Resetting Network Settings
• Unplugging Home devices (HomePods and AppleTVs)
• Updating device firmware(s) (iPadOS 18.5, audioOS 18.5)
• Completely resetting Homekit with Apple's own HomeKitReset mobile profile

All of this with no success at all yet.

At the moment I have 1 HomePod Mini (audioOS 18.5) connected to HomeKit, and I've tried updating from my iPad M4 (iPadOS 18.5).

Contacted Apple Support's phone line, and they were unable to assist (they said they will look into it, and call me back tomorrow, although I'm doubtful I'll get a solution).

[Edited by Moderator]

Original Title: Unable to Complete Home Update