The bridge is where the main Strategic game of XCOM 2 is: it even has it's own hologlobe. From here, you will contact Resistance cells around the world, respond to attacks and threats, and occasionally receive info on hidden caches of supplies and materials.
Every action here is accomplished by scanning localized targets: on each given option, there'll be a radar-like icon describing the time requirement, and any material requirements (Intel or supplies), Contacting a resistance cell in new areas should be your primary priority, as it gives you more options and funds. Afterwards, you can build radio relays to reduce Intel costs down the network of resistance cells. You will also frequently receive opportunities for additional supplies.
As each of these items do not happen congruently, but individually scanned, it is not required, nor recommended to try to get every cache of opportunity, but to focus on contacting and building up the Resistance network, as you will need a given sector to be in contact with you in order to discover and assault any Blacksites, to push back the Avatar project.
Your home base has it's own scan specialty: once a month you may change between Rapid Construction, Intel Gathering, and Rapid Healing for a small supply fee. Once chosen, you must scan at your base in order for the bonus to take effect.
The Strategic game is a balancing act of extending and empowering the Resistance with a limited amount of supplies. Again, the cache tip-offs happen regularly, so feel free to ignore them in favor of getting Resistance activities done.