You can take steps to lock down your smartphone and limit its ability to spy on you, since you only need it to hear what you're saying when you're using it as a phone. You can't do that with these smart home devices; an intrinsic part of their function is that they have to be always listening.
How do you stop your phone from always listening to you? It has a microphone and an internet connection. The hardware and software are closed source and out of your control. It is also orders of magnitude more powerful than a smart home device and is within listening distance of you pretty much 24x7.
If you are scared about an Echo in your house then you should be keeping your phone, tablet, laptop and 50 other similar devices locked up in Faraday cages at all times.
Using lineageos without microg at least severely reduces the chance for an "oopsie daisy yes so our microphone really was listenig the whole time and we accidentally used that data for targeting but hey, we're veeery sorry and you're getting a 50ct prime voucher ;)"
This is not about escaping every slight chance someone might surveil you, which one can't do anything about anyways, but to make make sure you're at least not part of a dragnet effort powered through the blackbox computer provided by a hostile entity whose only purpose for existing is recording your voice.
