I'll run down PoC involvement I do know.
There still was a fair amount of racism in the US in WWII. Black men were allowed to fight, particularly in the Battle of the Bulge side by side by white soldiers (which was the first time) which was the first time that was allowed to happen. (There was segregation before that point). Some historians argue that this fueled some of the civil rights movements later on...
The US also had Tuskegee airmen and though there is a movie about it, some say it's inaccurate, so it's worth going back to the source. They also suffered quite a lot of racism from what I know.
And despite Japanese being considered enemies, both British and US citizens of that descent fought in WWII. Imagine it this way: You're considered an enemy of the State and you're treated badly by the people around you, yet you're still fighting for your country. I know there is at least one autobiography about it. Japanese-British Soldiers were also treated poorly, which included bullying... (Most of the usual stuff add on "enemy" on top and there you go.)
George Takei also has narrated what it was like in the concentration camps (I rather call it that and then the Jewish/other groups "Death Camps"--I like the blunter language.) He made a musical about it which I wanted to see, but it's in NYC... and I'm not.
I read that Nazis allied with Japan out of "We don't like each other, but you've got your domain, we've got ours." The Japanese military was particularly brutal in WWII and the *majority* of the population now feels shame about it. (Not all... mind you, but there is variation in every population.) There is some stomach-turning stuff. For Japanese, what WWI was to us, WWII was to them. (Huge cultural shift in thought and change... including how to view War.) If you want to explore that aspect, what I remember are these key events:
Comfort Women (so horrible that I think people would protest getting it taught properly in high schools), Rape of Nanking (which is just a despicable look at HUMANITY in general... when I was studying it in class, we watched a documentary. Several people had to leave the room. I'll slap a really huge warning on this one. It's not pretty.), the Japanese experiments on US soldiers and enemy combatants (Which the US is not free of guilt over... since the result of those experiments were bought by the US), the starvation of Japanese soldiers in WWII (There is a Japanese movie about pretty much how the soldiers had to resort to cannibalism--fiction, but also representative of the way Japanese felt about the war--BTW, in Japanese available with English sub), Of course the atomic bombs (regardless of if it was "necessary" from a strategic standpoint or not, it's still horrible...), and General MacArthur for the recovery program. (I kind of view him as a narcissist... but... I may be a little biased.) Modern Japan History class for the win.
That should give you a bunch of key terms to look up. I have heard stories within the community that *some* Chinese and Koreans got out of the Concentration Camps by proving they were not Japanese, but that's pretty horrible anyway. (Mostly in Washington??? I'm foggy about that.) I know most of California did not get out of that kind of districting. Literally, the entirety of Little Tokyo in LA was ordered to evacuate.
They did later sue, but never got back the full value of their land, property, or the money lost by that move.
If you wanted to look at the racism, ethnocentrism, there is plenty of guilt to go around in WWII.