Same here: HA via Nabucasa works perfectly fine, so does google home with nest. After adding “Home Assistant Cloud by Nabu Casa” in Google Home, i’m stuck with “Could not reach HA Cloud…” as well.
I’ll contact the Nabucasa support, let’s see…
And same as for previous posters: My only reason to have bought a google Nest was to voice control my HA instance
EDIT: a simple reboot of Google Nest did solve my issue