Importing devices from google home?

You are of course right that there’s no way to import devices from a Google Home account over to SmartThings.

As far as these specific models,

I don’t think there’s a direct ST integration for Feit WiFi devices, is there?

You can get a partial integration through the Smart Life app, at least for on/off. See:

But you might not get dimmer control, it just depends on the exact model.