Oh, so what does going online in XBX actually entail for the game, then?
XCX used to have a 'squad report' feature that would pop up in the top left corner where achievements pop, this functioned like a game chat, but this worked through miiverse so that no longer works. I used to use it to tell people where squad tasks were or to ask to squad up for missions.
The other parts of the online are Squad Tasks, which are like a bounty where you are tasked to collect items or kill enemies of a type, tracked on the bottom right, doing so awards Reward Tickets and boosts your ranking in the Division Drive, I think this is shared with people in the same division as you and you all get Reward Tickets from anyone completing them. You can use Reward Tickets at the online terminal to purchase enemy materials (VERY VERY VERY helpful, especially when doing endgame crafting for the Ares 90), and completing tasks also awards event passes which allow you to challenge the Global Nemesis.
The Global Nemesis is essentially a raid boss where you squad up online with other players and deal damage to the boss. It has a hundred thousand lives or something, and you have a timer to kill it as many times as you can, rewarding some good materials and boosting your Division rank. There are only two different global nemesis (nemesi?) which are low level reskins of the game's two highest level super bosses and are technically non canon.
There are also online missions where you team up with other players to kill enemies in linear levels, which also rewards materials and stuff. I think you can do these offline, and there are a bunch of unique enemies and items with little lore bits in these. It also lets you challenge story bosses again, its essentially the combat challenge mode from Xenoblade 2 that got added to 1 and 3.
It's essentially for crafting materials and stuff, there is a bit you can access without online but the game will be a lot harder to grind when online goes down, luckily Cemu has cheats to enable Squad Tasks and Global Nemesis offline.
Your Division ranking get scored at the end of the week and based on your division's standing you get bonus rewards, also contributing to your division nets you bonuses as well. The game really doesn't tell you this stuff, so its worth reading the e-manual which is actually really informative and has a button in the game to open.