PureOS Kernel is not only supposed to read actual BPP-L503 battery cell voltage/capacity, this Linux Kernel indeed “configures the gauge with correct values” or reads exact stage (capacity number for example) from within Librem 5 belonging battery, from the very precise bq25890-charger connected to the inserted Librem 5 battery (even when brand new fully charged to exactly 4.20V or properly serviced one just inserted) during booting phase into PureOS GUI. IMHO, here related Linux Kernel does what supposed although other HW related questions being quite complex to be understood right out-of-the-box as self-explanatory (for any end-user):
Perhaps right time to clone/upgrade: Librem5 / firmware-tps6598x-nonfree · GitLab, and if not, etc., just my two cents anyway.