he was squeezed out of a ketchup bottle sonic's father used on a chilli dog

red

No he is red because of anger

red

definitely a new yorker

red

red

Red.

It fit with his character. For instance, pigpen on charlie brown is dirty or dark tone because he is nasty all the time. Just like Anton is from busting through walls and debris.

this might sound out of nowhere, but if its about how red skin is commonly associated with stereotypes of indigenous people, i brought this up a while back in Summit's discord server (which i do not recommend going in now), and Tony said that is absolutely not what they were going for with Anton as a character lol. he followed up saying its all good and that its good to have talks like this.
so he definitely isn't at all meant to be native american at all. the red skin is from the anger and MAYBE his spirits, and besides, people in the antonverse have straight up green and blue skin.
like i said in my other reply, hes very likely a new yorker based on the city setting and his accent.