This is why I would never invest too much into Smart Home. While my phone may be expected to last for a few years only, I don't want my house deprecated because of a takeover/bankruptcy of a company.
Reconsider. I'd say these are two safe options: 1) Go with a cloud service using products exclusively made by a single major company, like Google or Amazon. This is simpler to setup and maintain but more expensive. 2) Go with an open source solution, like Home Assistant. Cheaper option with more control but requires a lot of time to learn, setup and maintain. Both options should be considered safe at this point. Edit…
Making any company a single point of failure is a bad idea. You are basically giving up your freedom of choice for maybe some convenience, but don't confuse it with guarantee of sustained service.