Just to make sure those reloading apps are not because of app itself needing reloading. Leaving inside the RAM is one thing, being hibernated by iOS and lost its functionality and require a refresh is another.
One of my games I used to play works more or less like what you want: resume where I left off. All it needed was a reconnect and voila.
I think YouTuber’s demonstration is slightly misleading cause it varies greatly from app to app.