This app was mentioned in 19 comments, with an average of 1.26 upvotes
You can do this with an Android phone; https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
You can make any hotword you want for this and will access Alexa as if from your Echo.
You can on Android using Alexa Listens - you can have this set to any keyword you want. However, you'd have to make routines etc. play out of another echo device instead of the device you spoke to
I did find this android app that is supposed to enable Alexa to always listen on your Android phone, and yeah I could activate Alexa without opening the app, but only 10% of the time, so it's useless as well lol
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens This one claims to work on Android Wear. However, I found it well after giving up on smart watches, so I didn't test it on one.
This app gives some of the functionality though it's more intended as a demo it does work. I couldn't get certain things to setup on it such as my Philips Hue lights. https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
I did the Alexa integration on my little home system. (just one room with AVR and ~5 lights)
I only have a FireTV stick, but if you use a third-party app, you can send the voice controls that way. The app authenticates to the Alexa service, then it can send her commands from your phone's mic.
I used this one - https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens What I found the best about this is that it includes an Android Wear app. So I can control my house from my wrist. Slick.
Alexa through this app might work, but you'll likely be better off sticking to the Assistant.
Haven't tried this for a while but looks like it's had several updates so it now works in UK etc.
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
Use Listens for Alexa can use any hotword you like.
For those of you on Android, here's a similar app for WearOS that I use.
Could an app like this work? https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
No idea how apps work in wearOS
I use Alexa from my watch with Listens for Alexa.
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
None of this Google Assistant silliness.
Haven't tried it but this app can supposedly do it:
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
Try Listens for Alexa.
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
I have is working on my watch. It's tied to one of my hardware buttons.
You could try this app with AndroidWear watches; I just installed it to check it out but haven't launched it yet so can't speak to it's effectiveness.
Alexa Listens: https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens&rdid=com.willblaschko.android.alexalistens
There's also this watch: http://bgr.com/2017/05/04/alexa-smartwatch-on-iphone-android-mvoice/ or this one: http://www.imcotechnology.com/
https://play.google.com/store/apps/details?id=com.willblaschko.android.alexalistens
This app used to work the last time i was still on AW. Not sure if it still works.