HomePod mini Siri says One sec/Working on it for every command, while AirPlay works and Siri on iPhone works. Factory reset and USB restore already performed, including testing on a different Wi-Fi/hotspot.
Don't use a Hotspot at all and make sure your WiFi Network is using a 5Ghz only network, instead of the multiband 2.4Ghz/5Ghz frequency. You don't want your HomePods/iPhone to connect to the 2.4Ghz frequency because that one has inherent problems with interference and limited channel bandwidth when multiple devices are in the area. It is only still there for backwards compatibility with older devices and not needed at all for your Apple devices.
HomePod mini Siri says 'One sec/Working on it' for every command
