Maybe I misunderstood what you meant.
Display localhost:8080/demo/，实际访问的是localhost:9000/microsevice/demo in the user’s browser URL.

server {
   listen 8080;
   location ^~ / {
        # 如果需要的话
        #proxy_set_header Host $host;
        #proxy_set_header X-Real-IP $remote_addr;
       proxy_pass http://localhost:9000/microsevice/;
   } 
}

Displayed in the user’s browser URLlocalhost:9000/microsevice/demo，实际访问的是localhost:8080/demo/.

server {
   listen 9000;
   location ^~ /microsevice/ {
        # 如果需要的话
        #proxy_set_header Host $host;
        #proxy_set_header X-Real-IP $remote_addr;
       proxy_pass http://localhost:8080/;
       # 最后那个 / 是必须的。
   } 
}

Yes, use proxy_pass