The universe is expanding faster than the speed of light. So what exists between us and distant objects is the future distance between us and distant objects.

Imagine chasing a balloon floating north on a long airport treadmill pulling you south. It's faster than you could ever hope to run, so the distance between you and the balloon will only ever grow.

This is a sort of analogous metaphor for what would happen if you tried to go to distant objects.

Will they be similar to our universe or have less energy because inflation continued for longer?

Likely similar to ours. The energy from inflation came from energy that is inherent to the fabric of space - dark energy. So it was not diluted.

But what if we tried to go there anyway? What exists between us?

First there is distance. New space would be created faster than we could travel there. There would likely be other problems. For example, matter would not be stable enough to form atoms and probably wouldn't exist at all. In the inflation universe, the particles are hypothetical "inflatons", not the particles we have.