With many "smart" devices, if you block their outbound traffic they won't work. It's because they store their data on the company's servers. This is so if you have for example an app that monitors your backup generator at your vacation home, you can monitor it from anywhere. Which is a useful feature but now the generator company has you by the short hairs. They can charge a monthly fee. They can take your data and monetize it by selling it to data brokers who combine it with other data they have to figure out when you're home and when you're at the vacation place, and sell that to advertisers. They can decide they no longer want to support the service and shut it down. That's happened with some smart thermostats. A rival buys the company and bricks everyone's thermostat.
I bet they're using port 443 so they blend in with all the other web traffic (and make it through the ISP's outbound filtering). They don't need to accept any connections from the outside to do what the manufacturer wants- they can poll the servers.