If it's not compatible with home assistant it's worthless junk. If it requires their app to function, it's worthless junk... you are buying a product that can be rendered a brick at any point, and there are literally hundreds of examples of companies doing exactly this.
Stop buying them, unless you own them and control them.
They need to be connected to their servers to be set up... worthless junk. At least you've learned a valuable... albeit it, expensive lesson. There is no reason at all to allow these devices to be at the whim of some company. It's a hill I would gladly die upon, and the only things in my home that connect to the internet are my solar/battery system and my thermostat... both can be integrated into home assistant and only the solar/battery system sends any data about generation and battery health, I've even isolated onto guest wifi network to keep it free from the house.