Well, I believe your problem really is that you haven’t invested in a proper smart home infrastructure but effectively created a zoo of various gadgets that claim to be smart-home capable but really have a limited shelf-life. So you problem will not only occur when you move out, but also when the vendors stops the (cloud) service in probably 2-3 years.
Let me explain: right now, you use probably half a dozen of apps to control different aspects of your home. That’s because every vendor’s gadget comes with it’s own app that doesn’t talk to anything else than the vendor’s device or cloud service. That is not smart home, that’s just the normal gadget addiction we inherited from Laptops, Watches and Smartphones. These are not focussed on your infrastructure but on your personal experience (and data), even if they claim otherwise. That’s why you face these problem with aspects that are not a problem with small, mobile devices but become a nightmare when we talk physical infrastructure.
A proper way to do Smart Home is with real device manufacturer, that has an ecosystem and not just 4-5 devices. HomeMatic for instance is such an ecosystem, on it’s own radio frequency (833 MHz) that works without a cloud, without WiFi and without apps (of course all these things can be added). It integrates in your home in a way so that everything continues to operate as normal – you continue to use the same light switches, the same wall sockets, the same consumers. You just install a couple of actors concealed and hook them up to the physical wiring, handles, switches etc and let the system handle the rest. When you “hand over the keys” you simple explain where all sensors and actors are and keep power to the CCU2. Done.
This behaves properly when there is no cloud, no wifi, no gateway and comes back cleanly when there’s a power outage. Plus you can still override with physical manual control.