The reason no black box exist is that current is useless for monitoring the system health. It's only use is for experimenters and the exceptionally inquisitive.
Voltmeters are used to monitor system ad battery health.
And if you are going to design such a system, don't use shunts. Use Hall-effect sensors. Nobody uses shunts except when the shunt is a normal cable (eg, ground strap or +12V feed).
Old internal shunt (series) ammeters went out of fashion decades ago, and external shunts not much later.