If you don’t mind getting really hacky, some people set up an inexpensive android device next to an echo and use LANnouncer so they can get smartthings integration with devices that have echo skills but no other way in. Such as the Frigidaire smart air conditioner or in this case the Wi-Fi roomba. It may even be possible to have web core do the text to speech, I’m not sure. But the point is that you have your routine or web core trigger the android device to speak the command and then echo responds to that.
Like I said, not exactly an elegant integration, but it works for some people. 