Edit: I change the title of this thread because I also came up with another idea you'll see posted separately down below.
I feel like a good way to keep people occupied in this game would be to have some kind of events with a war contribution meter in the game every once in a while. You know something that is similar to the web events the JP version gets to a certain extent, but feels like it has purpose, that feels like your doing something not just for items, but because it feels like your making some contribution to keeping the ARKS in Central City alive.
Central City should feel like it's in real danger at times, and we should feel like we're actually protecting it (only having us magically save the city all by ourselves in a cutscene would make it feel cheap), together as a team with all the other players, not as one person with plot armor. The DOLLS sometimes literally spawn right outside the city so why would they not be attacking it if they attack us if we set foot outside the walls.
The meter could unlock access to items for us to buy more items in a shop with some kind of event currency but the point of the event should be to feel like we're doing it for a purpose, not just for those items. And no I don't mean a defense op (which one was announced in the roadmap already), there would be nothing we actually have to defend, but the city would look like it's being attacked.
Yes this idea is heavily inspired by games like Adventure Quest Worlds, but they are not the only game to do that (Warframe has had similar events too), but I don't want it to be a carbon copy of AQW, like I don't want to have to click a turn in war medals button, I want the progress to be directly counted by enemies killed. Either way considering we have seen that it is possible to track players kills in this game from the JP WebEvents, I don't see why this couldn't be possible.
For the city being attacked part it would basically be like a seasonal lobby where rather than nice decorations, it's fortifications and maybe some projectiles hitting the walls or something. And then the rest would be like the events in base pso2 that rewarded rising weapon badges dropped by whatever our target enemies might be.