A similar question that was answered by u/nompilo appeared here, and may lead you to read James Whitman's Hitler's American Model. The major argument being that the Nuremberg Laws seen in 1930s Germany had inspiration from Jim Crow laws in the segregationist South, particularly those relating to legal status and rights of races deemed to be inferior by state and local authorities.

I did undergraduate research on Hitler's boyhood fondness for the "cowboys & indians" style of pulp fiction that was popular in the late 19th century, particularly the works of Karl May, the notable German writer who placed many of his works of fiction in the old American West. The best and most clear delineation would be to separate Hitler's conception of the archetypal Native American soldier from that of the Native American race, as these two ideas offered different interpretations.

Hitler sat in for one of Karl May's lectures in Vienna in 1912, and was an admitted fan of his writing. He was known in childhood to fantasize with his chums about the trope of 'soldiering on the wild frontier' (despite the fact that May's depiction of the American West was different from that which American writers of the same time period had worked to fantasize or romanticize in their Western novels, as May portrayed many of his Native American warrior-archetype characters with protagonistic, noble, and what could be considered desirable white character traits that were sometimes a massive departure from the stereotypical American depiction as either the ignorant noble savage or the scheming, bloodthirsty fiend that could only be pacified by conquest). The popular Mays character Winnetou best illustrates this conception, as the Apache warrior was portrayed as red outside but white inside, adding layers to his internal conflict of being colonized by whites but fitting in best with the white colonizers. Mays work was immensely popular in Germany for much of the late 19th and early 20th century, and influenced the conception in Europeans' minds of Native American soldiers having their best merit when sitting next to you in a foxhole. Partner this with the traveling Wild West expose shows that passed throughout Europe with the likes of Buffalo Bill in the late 1800s, and the portrayal of the Native American warrior-archetype as being fierce in battle while simultaneously suffering from a complex identity crisis. If we take May's literary influence at face value, the conception becomes possible to imagine as present in the minds of Europeans in Hitler's time.

As to Hitler's personal views on Native Americans as a people, the answer becomes a bit more murky when you compare the archetypal native warrior that May depicts in literature to the tenets of another popular early 20th century discourse: Social Darwinism. Hitler was undoubtedly aware of the contemporary notion that superior races were deemed better fit to thrive in the environment, and subsequently projected this notion in the 1930s Lebensraum campaigns that aimed to seize territory from the peoples of Central and Eastern Europe - particularly Poles and Slavs. On one hand, there is the supposition that Hitler carried Mays' image of the Native American soldier as steadfast, gritty, and highly valued for their merits in battle. However, the notion of Native Americans as a people was a much different story, as they, by virtue of their inability to fend off the vastly superior whites, were simply following suit to the "natural order" prescribed by Social Darwinist theory.

Sources:

Cook, A Researcher's Guide to Karl May, German Studies Review (1982) Cracroft, The American West of Karl May, American Quarterly (1967) Fischer, Hitler and America, UPenn, 2011 BBC Radio 4, Hitler's Favorite Cowboy, 2013

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