Since my retirement, I have replaced many batteries in many smart phones for friends and disassembled quite a few laptops to replace keyboards, memory, etc.
The pixel 4xl battery replacement is quite simple with some torx screwdriver bits and plastic tools to pull off the back cover (torx screws hold in a lot of brackets). The battery itself is about 30 bucks; not a bad price.
Also, out of curiosity, talking with someone in a local store about replacement, I was told about 70-80 bucks, including the battery...not a bad price.
Is it for everyone? Probably not; however, for many it is a simple few hours and all is well again. Those special tools are very inexpensive.
However if an old retired ex Federal gunslinger can do it at 73; most anyone can. Besides, it is almost as fun as disassembling and cleaning handguns and a lot cleaner.