Yes crdroid has that implementation of pixel port. I'll try n implement but depends on free time I get. Also A13 just around the corner so let's see.I'm not sure if this is of any help at all, because the ROM I'm using is not available on GitHub, but I just checked this battery widget on crDroid, and it works for me flawlessly.
Here's a link to the zip of the build I'm currently using.
crDroit itself has a GitHub page, but they don't officially support Pixel 4a.
Maybe you can make use of either of these sources.