Notes for setting up userspace pd-mapper, in case they are useful for anyone:
There are arch PKGBUILDs here, as Johan mentioned: https://github.com/andersson/arch-packages/tree/master/pd-mapper-pkg
You will also need to compile the qrtr library. You don't need qmic. The repos are here: https://github.com/linux-msm/pd-mapper and https://github.com/linux-msm/qrtr
You will need the `.jsn` firmware files as well, and they are NOT available in the `Seraphin-` repo, you have to copy them from Windows. Make sure you don't compress them with zstd, pd-mapper only supports xz and uncompressed `.jsn` files.
After setting up the pd-mapper daemon the battery status seems to be updating, but still only like once a minute, I am not sure what reporting frequency the underlying glink api is capable of.