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.