I just looked up the charging standards for the Nexus 6P - wow! I had no idea that google had come up with its own proprietary charging standard. I don’t know of any Anker products that specifically meet that standard, but you might want to try your luck with a USB-PD port. I would think that would be the best chance for finding a charger that will still fast-charge your Nexus 6P (and also your wife’s Pixel). Any of the Anker wall chargers that have a USB-C port should support USB-PD.
As for cables - all of the Anker cables that I have tried support some variant of fast charging (Qualcomm Quick Charge for USB-A to Micro-USB/USB-C and USB-PD for USB-C to USB-C). I think that, if you buy USB-C to USB-C cables, they’ll support USB-PD, and hopefully charge your 6P at a decent speed.
Keep in mind that this is all conjecture - my S8 uses a Qualcomm Quick Charge standard, so I don’t have any personal experience with this.
One final note: my phone will fast charge using the PowerIQ standard that Anker offers, so you might still get a decent charging speed off of a PowerIQ port (although I think that it is less likely to be successful than a USB-PD port).