Confused about reverse proxy flow and 'trusted_proxies'

Nextcloud version (eg, 20.0.5): 21
Operating system and version (eg, Ubuntu 20.04): Ubuntu 20.04 + Docker
Apache or nginx version (eg, Apache 2.4.25): Docker Apache Image (latest)

The issue you are facing:

`I have been attempting to login into the Talk app, but the ‘Grant access’ Screen loads endlessly and some users are reporting problems logging in with nextcloud behind a reverse proxy. I have come across this article: Reverse proxy — Nextcloud latest Administration Manual latest documentation

However I am a bit confused on how to actually set it up with my workflow.
Here is how things work for me:

Dockerised Nextcloud Instance (docker-compose.yml)

Docker-Compose File
version: '2'
 
services:
  db:
image: mariadb
restart: always
command: --transaction-isolation=READ-COMMITTED --binlog-format=ROW
volumes:
  - ./database:/var/lib/mysql
environment:
  - MYSQL_ROOT_PASSWORD=HIDDEN
  - MYSQL_PASSWORD=HIDDEN
  - MYSQL_DATABASE=HIDDEN
  - MYSQL_USER=HIDDEN
networks:
  - default
 
  app:
image: nextcloud
restart: always
links:
  - db
volumes:
  - ./html:/var/www/html
environment:
  - MYSQL_PASSWORD=HIDDEN
  - MYSQL_DATABASE=HIDDEN
  - MYSQL_HOST=db
networks:
  - web
  - default
depends_on:
  - db
  - redis
 
  redis:
image: redis:alpine
restart: always
networks:
  - default
 
  cron:
image: nextcloud:fpm-alpine
restart: always
volumes:
  - ./html:/var/www/html
entrypoint: /cron.sh
depends_on:
  - db
  - redis
networks:
  - default
 
networks:
  web:
   name: web
  default:

I then have a Nginx Reverse Proxy Setup in front (NGINX Reverse Proxy Manager). Everything works for now but the only thing I can’t get working is logging in to the Talk app, so I want to properly configure Nextcloud to know it is behind a reverse proxy. How can I accomplish it with my setup:?

<?php
$CONFIG = array (
   'trusted_proxies' => ['nginx-proxy_app_1'],, #What would go here? The reverse proxy hostname docker?
  'overwritehost'     => 'localhost', # The container's hostname? Localhost?
  'overwriteprotocol' => 'https', #
  'overwritewebroot'  => '/nextcloud.example.com', #I assume this is my reverse proxy?
  'overwritecondaddr' => '^10\.0\.0\.1$', #And this one baffles me
);