To go to the end of the universe, I don't think we need to look for superluminal speeds. I think an interstellar travel machine needs to dilate local time. Dilate local time can lead us to travel infinite distances even with a small speed, at that point, it is space and time that allow the machine to be brought where it wants to be in an extremely short time!
I think there are areas of the universe that are conducive to allowing us to travel in time, these special areas dilate time and therefore create shortcuts in space. I'm not talking mainly about glass holes!
We must now, in my opinion, build machines that are not intended to reach the speed of light but we just need, for example, a tenth of the speed of light to look for these special areas that are not very far from us I think and then enter them!
By my calculations, we can travel ten to the power of thirty-eight meters in eighteen hours, ours!