Transfer Texts / Group Messages from Nexus 6P?

Yes. Just hook up a cable to the included adapter and hit transfer. The phone will walk you through it making it easy.
 
If that doesn't work for you, check out Carbonite's SMS Backup and Restore. I always use that when I go from phone to phone.
 
I just did a reset on the Pixel XL and did the cable copy. I only problem is that it transfers text messages only, doesn't get group or picture messages, so it is kinda worthless to me. I may reset again and do a fresh install, because it also auto downloaded ALL of the apps I had on my 6P. Samsung Smart Sync grabbed picture messages and group messages when you backup and restore with it. Oh well, no big deal, just would have been nice.