No. Here's the dime tour version.
We don't know exactly what it will be like, but we do know, as you pointed out, that there will be no sin in heaven but that we won't be robotic beings. The difference is that we will have a different nature. Something about having fallen and then being restored to glory is going to be different than the state Adam was in having never known evil and yet excersising his free will.
Exactly what defenses will make this possible we know not, but we know that one way or another the work of Christ to sanctify his people will be brought to completion and that they will never more fall away from him.
Your speculation is based on an incorrect understanding of the nature of man and sin in the first place:
My only idea is that since the Devil will be chained for eternity, there will be nothing to tempt us [...].
Christianity's understanding of sin is not based on outside forces tempting us, but on an imperfect nature that cannot help but sin. Adam could not have helped but eventually sinning, snake or no snake. Free will is not so free as many people believe: we are bound to act according to our nature. We are not "free" to act according to a nature that we don't have. We aren't "free" to teleport just because we would will it. We are not "free" to not sin because it is part of our nature to do so.
The difference in heaven is that our natures will be regenerated into something completely different than they are now and we will be free -- but only to act according to our regenerated natures. Which won't be dragging sin into the presence of God.