We are taught that God is love. His love is such that He gave us free will to either love Him back or not. We even have the choice to turn our back on Him. Not believe in Him. And to preach and teach against Him and His existence; and to mock those who believe in Him. His love is such that He allows us all these luxuries and freedoms to choose as we wish.
The devil was one of God's loved creations. He chose to rebel and love God no more. God allowed him this choice. I guess, (although I have no proof of this), God still loved him despite the devil's rebellion. But it was the devil's free choice to go his own way.
Many humans choose the same path of the devil. And, I guess, are still loved by God.
But then, one day, comes decision time. We die either in love with, and in gratitude to, God, for all He has done for us; or in enmity with God.
It is this free choice at death that leads us to Heaven or Hell. It is as if God says to us: "Thy will be done. You choose to go to hell; then go!" (To quote C S Lewis).
Does God still love those in hell, including the devil? My guess is probably yes. If God is love, then He loves everyone; even those who rebelled against Him.
Will God forgive those in hell and welcome them back to Heaven, including the devil? There is no Biblical evidence or teaching of that. In Christ's parable about the rich man and poor Lazarus at his door, Jesus says that there is a great chasm between Heaven and Hell and neither side can traverse it. So it does seem that those in Hell are there for eternity since Jesus taught so. They are there for eternity because they chose to go there. The gates of Hell are locked from the inside by those who would rather be there, and had made that choice at the time of their death.
So to answer the original question: Does God love the devil? My guess is yes, as He has always done, despite his rebellion. Just like many parents would love a child who goes astray.
Will God forgive the devil, and all those who rebelled, and welcome them back to Heaven? There is no Biblical evidence or teaching of that. But then everything is possible to God. The devil and his followers can be forgiven ... ... ... if they really want to!