Where is the devil right now?

Answer 1

It seems that even today we do not really know what the devil is supposedly doing or where:
Satan entered post-Exilic Judaism as the 'adversary' but under the instructions of God, as his loyal assistant, tasked to test the righteousness of the faithful. If this is correct, Satan goes where God sends him, just as we see in the Book of Job.
In Christianity, Satan evolved to become the devil, seeking to cause the faithful to deviate from righteousness and to destroy God's kingdom. Satan continued to evolve throughout much of the Middle Ages, at time as a figure of fun and sometimes with changes in how he exerts his wicked powers. The ambiguity continues in belief today, which is why (i) he can be in hell being punished for his disobedience, or (ii) in hell happily punishing the souls of the wicked, yet also (iii) wandering the earth tempting every person alive today.

On the other hand, as the Jews did not even know about Satan until around 500 BCE and as they still see him as a loyal assistant of God, he probably does not really exist. If he does not exist, then the devil is only to be found in our imagination.

Answer 2

Nobody can answer this.