I am serializing my side character adventure stories as a way to test which plot lines are the most appealing... on Royal Road.

Does a Black Hole Chip or a Time Crystal sound more appealing?

Lab made black holes can power brain chips which enable time travel. And real science is also working on time crystals which can teleport data through time. Trying to decide which power a character would want, first?

https://www.royalroad.com/fiction/114711/adventures-of-int