Also - our standardization is not the greatest, so I actually want to rewrite the entire URI, which is why I have ^/(.*) as the regex. However I don't think the $1 in the replacement string will still apply to the original URI. Would this work?

location ~* /v1/device/(.*)/ {
rewrite $uri /api/v1.0/download/$1 break;
proxy_pass http://api.domain.com;
}