That being said if you know how to run docker you can just proxy the video feed to vlc pretty easily but most parents don’t have the time for that
To view a baby camera over the internet someone has to run a server. To run that server costs money. (If you think that the actual server/bandwidth cost is negligible, make sure to also include the cost of keeping the team employed to maintain those servers.) Someone has to pay for that. Based on what you say it sounds like the Nanit baby camera degrades gracefully to the local only features if you don't pay the subcription. That is kind of the only honest way to run a business with a connected component.
As long as they were up-front about this at purchase I can't see a problem with that.
How is this different from Snoo? Quite frankly I don't see how the baby rocking function requires a remote connection. It should be totally implemented locally inside the basinet and there should be no on-going cost. Therefore the only reason they might lock the feature away is due to greed.
In an alternate universe with better technology, this would not be true. You'd connect to a host over the WAN just as you connect over the LAN. Unfortunately ISPs and firewalls and NAT have made this much more difficult and complicated than it should be.
My heart aches when I think about how many company servers are out there running only to facilitate "doing X with your LAN, but from the Internet".