with 100,000,000 years, I would've probably started offering the unlimited food supply to a fictional god, start a cult following with me as the sole member and try to summon the guardian deity of the joint time-suspended space, transcended the dimensional rifts and traveled to the interstellar wormhole, find ancient era people of the parallel past, teach them agriculture, domestication and architecture, build the pyramids and temples that will house the image of the guardian deity of the suspended time-space, teach them hierarchy, weaponry and colonization. I will pass down an ancient relic created from the guardian deity, a red button that shall be passed down for millennia on a self-fulfilling prophecy to generations of hermits of time until it reaches the past-present-parallel future me.
... go back, sit down, relax and watch some anime with my guardian deity buddy that will somehow become my stand and then use za warudo against anyone and everyone that dares disturb my utopia.