Not quite a multimeter, but here's a power meter. I've seen essentially the same meter under various brands. It's designed to go inline with a DC power source, and it measures voltage, current, power, watt-hours, amp-hours, and a few other statistics.
https://powerwerx.com/watt-meter-analyzer-inline-dc-bare-wireThis particular one has bare wires on the ends, but from that same website you can get it with Anderson Powerpoles, or solar panel connectors. Of course you can solder or crimp other DC power connectors onto it if you prefer. If the power source it's connected to has at least 5V, the meter will power itself from the same power source that's being measured. If you don't want to put any parasitic load on your power source, or if your power source is less than 5V, you can power the meter from an external source using the auxiliary power connector.
I have one of these with Anderson Power Pole connectors, and I find it very useful, mostly for keeping track of my use of rechargeable 12V batteries for ham radio applications.