Android is one of the most popular mobile operating systems. However, some Android apps can cause security issues if not carefully handled. They can be badly written which leaves a lot of security holes for intruders, or itself acts like a malware/virus. Therefore, before installing an Android app, one need to do some checks to make sure it won’t cause security issues.
Firefox for Android does not provide a UI option for users to to configure Firefox to use PAC file for proxy settings, but we can use the about:config page to achieve this goal.
Type about:config into your Firefox address bar, and you’ll see a list of options below. In the search box, type proxy to list all options related to proxy. There are two notable options listed here: network.proxy.type and network.proxy.autoconfig_url. Change network.proxy.type to 2 and network.proxy.autoconfig_url to the URL of the PAC file (Tap on the edit box below the configuration option twice to start edit the option). Close the about:config page and now Firefox should use the PAC file for proxy.
To configure the proxy of Firefox on Android using a given proxy server and port, please see this article.