All the megacorps have gone this direction.
Amazon is going to give you a constantly improving Alexa system and ecosystem and in return you are going to let them use sidewalk in most cases.
You need to be careful about open wifi which despite the claims is different - traffic will egress as you - so if someone jumps on and does some stupid stuff, you can create a fair bit of pain for yourself.
Most folks experience free improvements to echo after purchase. That is part of the value people see in these devices. The network effects get stronger with time. All of the use of these systems requires agreements to TOS that mean you really don't own / control the device, amazon does. Worst cast, when the megacorps close your accounts, you can actually lose access to lots of stuff that it feels like you "own". All your photos, all your email, maybe media content, books etc.