The timelineverse is a kind of universe with 2D time instead of 1D time. 2D time in this universe allows for infinite timelines, hence the name.
With the extra dimension of time, life forms in this universe can ALREADY have technology impossible in our universe as anything can happen in any timeline in this universe. An infinite amount of timelines have extremely advanced technology, an infinite amount don't. Another infinite amount don't even have life in the FIRST place.
Without a special kind of technology, a timelineverse would look just like an empty void to us, but with TIMELINE TRAVEL, we can find stuff inside the timelineverse when traveling into the right timelines as an infinite amount of timelines also are devoid of anything.