They're hardware projections into your living space of a massive system run by Amazon. It's the massive system that open-source will have trouble replicating.
Most people use Echos as voice controlled music players with occasional smart assistant functionality, this shouldn't be too hard to replicate in OSS. You could argue that the extend to which they're not making you buy into the Amazon ecosystem is a major failure of the product line.
It's still honestly amazing to me that people buy, or want, devices like this, even before considering the downsides. I mean, I don't even like leaving voicemail messages. So the idea of talking to nobody in particular, within my own home, to cause something to happen, totally freaks me out. I really don't need more excuses for physical laziness, either.
I removed my Google Home; IMHO, it got worse at processing voice commands over time, and I didn't use it that much.
However, when it was working well, it was nice to be able to set a timer handsfree when my hands were busy. And when running a recipie where the measurements are inconvenient, I apprechiated being able to access unit conversions without context switching to a computing device (memorizing unit conversions could fill that gap).
I'm not in a rush to replace the device, but if I hear about a device that can do those things in an offline way, I might consider it. None of the online features were useful or reliable enough, and by their nature they would be changing all the time ... having them was a negative.
False positive wakeword triggering was annoying too. But maybe a talking timer would have a wakeword that was more specific.
You can have a timer and unit conversions using your phone, but perhaps not hands-free. It might work for you, I am not sure. I wonder if one could make it hands-free though. If it is in very high demand, I might just make an application. :D If it does not already exist, of course. What about using an LLM though? You can talk to them, so that could be considered hands-free.
I don't want to talk to my phone... and if I did, the easiest path would be google assistant, which is likely just as bad as google home.
I don't want an LLM either. I want a very constrained command list that is consistent and doesn't change. Yes, you need some voice to text magic, but 'set a timer for x minutes', 'cancel timer' maybe something to have multiple timers. And also 'convert X teaspoons to ounces' maybe with sometimes things like 'how many cups of flour in a pound' (which is a not quite right question to ask, but I still might ask it)
> If it is in very high demand, I might just make an application. :D
If I've learned anything from my years on the planet, if toast0 wants it, it's not in high demand. Sorry!
I know a few people with Echos and I don't think I've ever observed them being used to order stuff. Music, answering trivia questions, timers/appointments, sure. This is anecdata of course but still.
(I didn't count music as buying stuff since it's a flat rate streaming service.)
1. https://www.home-assistant.io/voice_control/