An official OEM battery for the Pixel 7 along with all the tools you need is $50. It is not expensive. The process to replace it is easy. Certainly nerve racking the first time but I've opened up my pixel phones at least 6 times now and it is pretty trivial (on the non-folding pixel phones).

https://www.ifixit.com/products/google-pixel-7-battery-genui...