The Google Assistant integration we have is the one on the phone. Basically when you press flic then the voice assistant on the phone will open up and begin listening for a voice command.
Google Home does not allow third party triggers in their ecosystem (yet). They were planning to add support for buttons some year ago but for some reasons dropped those plans. Maybe because they want people to use their voice, I don't know.
We have direct integration with IKEA Trådfri and their Sonos speakers. Deltaco is white labelled Tuya SmartLife devices, so I guess you can use them through IFTTT.