After learning a lot about device tree and kernel builds I have a patch that enable the usermode spi driver for mnt debian kernel package.
As well as a minimal change to the lpc firmware that fills the spi transmit buffer with basic battery stats.
And a quick python program (that should be rewritten and made a kernel driver instead) that reads the battery information from the spi device.
Once my account is approved in gitlab I can put a PR out for the kernel and fw changes while I work on a driver.
A more advanced design that implements a command and poll structure is ideal, but that requires adding spi interrupt handlers to the lpc since the spi buffer is only 8 bytes. This design fits the battery info in the 8 bytes making it trivial for the lpc to fill the byte buffer with the stats at its existing poll rate.