

As long as the repair shop is reputable it’s not too hard. I was looking at options on iFixit when I first heard this update was coming down the pipeline. I guess I am lucky that mine was already a refurbished unit when I bought it so it looks like the battery has already been replaced.
https://www.ifixit.com/Guide/Google+Pixel+6a+Battery+Replacement/152516
I replaced a few batteries myself before in a Nexus 6 and a Pixel 4a. The guides really help as does having the right tools. It’s also helpful that iFixit offers genuine battery replacements.
https://www.ifixit.com/products/google-pixel-6a-battery-genuine?variant=39912699330663
Currently out of stock but that’s probably due to this update that wrecked so many users battery life.
They were the only phones I would reasonably buy due to their ability to be customizable… Yeah this pretty much puts a nail in the coffin of using a Pixel in my book as well.