I just bought a Magicsim nano dual sim adapter for my new Nexus 6P. Their web page said it worked for the Nexus 6P. Because I had two nano sims I also had to buy a separate adapter kit to fit my second nano sim into the magicsim's. I ended up spending just under $50 and waiting a few weeks for it to ship from England. I got it read the instructions and found that it is supposed to wrap around the first sim card and then you put the entire thing into the sim tray and push it into the phone with the "tail" of the thing sticking out. WRONG. On the Nexus 6P the sim card sits sideways in the sim tray. So I did the best I could and put the adapter under the sim card, put it in the sim tray, wrapped it back around under the bottom of the tray and they had to fold it diagonally at a 45 degree angle so it would stickout the front of the sim tray. Then I tried to push the sim tray back in but it was too thick. Wouldn't go in and I didn't want to force it. Nevertheless the adapter tore at one corner when I removed it. I emailed Magicsin and the next morning I received a reply that you're supposed to fold it diagonally for the Nexug 6p. Since I had tried that already, I tried folding it back over the top of the sim and then folding it diagonally again and inserting it. It went into the phone but wouldn't work. I looked at it closely this morning with a magnifying glass and one of the wires is torn.
I emailed them again and am still waiting for a reply. Short version: It might work for you. DON'T trust the instructions.