So I came to SmartThings via LightwaveRF products and Google Home. By this time I had already invested in LightwaveRF lighting dimmers and probably a dozen smart plugs I’d bought from Amazon (Teckin, 2Nice are a couple of brands). Everything works fine in Google home and I can control everything. I bought SmartThings so I could start adding sensors. I’ve linked my LightwaveRF to SmartThings and can see the dimmers in SmartThings. I can see the SmartThings, Lightwave RF and 3rd party products in Google Home. I can’t see how to add the 3rd party smart plugs in SmartThings so I can control them with sensor triggers. Google Home can see the sensors but they’re dumb - you can’t use any output from them in automations there - it needs to be done in SmartThings. There are lots of smart plug brands listed in SmartThings but not the ones I’ve got. Is there a generic way of connecting them. Surely all the manufacturers can’t be using different protocols? Any help and advice gratefully received.
Unfortunately many of them are. 
hence the first rule of home automation: “the model number matters.”
What’s the brand and model number of the sockets that you want to integrate?
In the meantime, try the community FAQ for some options that may work, depending on the specific model: