Hey there! 
At the moment, you can use a few different ways to connect with your voice assistant:
- A microphone and speaker, based on an ESP chip set, that can be flashed via ESPHome. An example would be the m5Stack ATOM Echo.
- Any old Android or Apple phone, tablet or smartwatch, that can run the HA companion app.
- A separate computer, that runs microphone and speaker and sends the signal in some way to HA. An example would be a Rhasspy server and/or client, that runs on a Pi (Pi Zero, Pi2, Pi3, Pi4).
There are other devices out there, that can be connected as well, but in the end, these boil down to the three things above. Eg. there is a nice little ESP-based speaker out there, the ESPmuse, that works nicely, but it is an ESP based device.
What I’d do is check where you want to put your mic/speaker and more important, how you’d use it. Eg. I have an ATOM Echo on my livingroom table, but I’ll change its location rather sooner than later, as we always have our phones and one tablet right there, too. Doesn’t make sense, as all mobile devices are running the companion app. So one click on the ATOM Echo is nearly the same as touching two buttons on my phone.
On the other hand, you’d likely not want to touch your phone, right after you have left the shower. This will be a good place for an Echo.
So my recommendation is: buy one or two of the ATOM Echo, flashing is really easy, and try them out. Get one or more (what you have at hand) Android or Apple devices and install the companion app. Give it a few weeks test run, to see, how you and your other household members are working with it. You’ll likely find some things totally different than expected, in terms of how people use these voice assistants.
I for one was sure, the mic on the livingroom table will be the most used device. Turns out, I was totally wrong. My wife uses her phone/companion app to speak her voice commands, and the next one in line is the tablet in the hallway. The Echos are fine and work great, but they are not yet located at the right places.
What I want to say is this: take your time, buy one mic/speaker beside the app, and test it. You’ll see quite quickly, where you need a mic, and where a mic is totally useless. And an ATOM Echo is around $15 each, so no real harm done in trying. If you order via the manufacturer shop, there is a discount code from NC available. 
Depends on where you live.
HA will still provide a functionality, where you will be able to use the ECHOs, but as you said, I highly doubt, wake word will be functional on these devices. But the combination Rhasspy/HA Assist will solve this for us: