Nexus 6P Battery issues after 2 years - next steps?

I bought my Nexus 6P from the Google Store shortly after it became available in November 2015. It's been a great phone - one that I hoped would never see the inevitable "end-of-life" announcements. Even after hearing that it would stop receiving all but critical Android updates, I saw no reason to replace it until very recently. About 2 months ago, the phone began to use an inordinate amount of battery over short periods of time with minimal usage. Now I can scarcely go more than a few hours without charging it.

If not for the lack of Android updates, I would just try to replace the battery, but I've noticed a wide range of results in doing this oneself or through a third party. I realize I'm way past warranty, and should probably just bite the bullet and buy a newer phone, but all things considered, I'd just as soon keep it.

So 2 questions come to mind: 1) what is Google's official policy toward Nexus 6Ps purchased from the Google Store with late-in-life battery issues, and 2) what have Nexus 6P owners typically done when faced with similar issues?

Thanks in advance.