shunt current measurement with less voltage
Yes there are ! 200A at 50mV (max) means a 0.25mOhm(max) shunt. A quick google for "0.1mOhm shunt" gives this datasheet (among others) that is 0.1mOhm, 350A/15W rated.

Of course I suppose you know that magnetic-based current measurements are also available, being hall-effect based (DC or AC, Allegro seels them for up to 200A as IC, and more than 1000A with a bit more involved design) or induction based (for AC only). Both types offer additionnally galvanic isolation.

In the end, unless you have strong magnetic interference, high current means lower acceptable shunt voltage (for given power dissipation) and higher magnetic signal : both favor magnetic field based over shunt based...