Are similar technical implementations possible in mobile game development on Unity?

Question

Unity

At the moment I am analyzing the mobile games market, and in the future I plan to switch to dev.
I have more technical questions for discussion, but since I have no experience in development, I turn to you.

spoiler

Вопросы будут по игре RAID. Можете мои вопросы и на другие игры проецировать, но суть не изменится.

Кто играл или играет в RAID знают о том, что он тратит очень много времени игрока (хотя, давно обещают ввести возможности для ускорения и т.д.).

По поводу КБ (клановый босс, либо в других играх будет финальный босс файт) - Обычно я затрачиваю 25-27 минут (там идет авто-бой, хоть это хорошо) на одного босса, а их 2, и выходит что у меня уходит почти час игры. В такие моменты нельзя свернуть игру, либо перейти на другую активность, то есть только смотреть на включенный телефон и ничего не делать

Hence the questions:
PS The game is implemented on the Unity engine

1) Is it technically difficult to implement the possibility of background / parallel activities in the game itself on Unity? Let's say, as an example of a fallout shelter - you can put a room upgrade (it will last an hour), and at the same time attack other players or engage in other activities.

2) Is it technically difficult to implement the possibility of background activities in Unity when the phone is locked or the game is minimized? The same example with the fallout shelter - before going to bed you put a room upgrade (which will last 10 hours), blocked the phone, and in the morning it remains to wait an hour until the upgrade ends. It's the same with a minimized game - bet on improvement, minimize the game and go watch YouTube.

I understand that these points may not be a priority for the company further. But I'm interested in the technical implementation, and not why the company does not want to make these points

Answer 1

1) Is it technically difficult on Unity to implement the possibility of background/parallel activities in the game itself? Let's say, as an example of a fallout shelter - you can put a room upgrade (it will last an hour), and at the same time attack other players or engage in other activity

Of course, I'm not an expert in units (not at all in the subject), but isn't the game server (which can be written on anything) processing these actions, but the client simply requests an update when the player opens the desired "activity"?
Those. in other words, while you are at war with another player, your game (most likely) does not know what is going on in your hideout and will request its state when you open it again. As an option - for greater "smoothness" the game approximately cached its last known state and shows it (adjusted for the elapsed amount of time, because it's elementary to calculate how much time has passed), simultaneously requesting the current state from the server in the background.

Answer 2

But in your examples there is no "background activity", a stupid check at startup if it's noon, then the building is built.

Answer 3

...
1) It's an illusion. Why waste resources on working in the background, etc., when all this can be simply implemented with some mathematical miscalculations. Well, it's worth checking AsyncTask, Coroutine.
2) Check also about the "Activity Life Cycle". To better understand background processes