A few more texts from Luke on heaven:
Luke 10:21 At that same hour Jesus rejoiced in the Holy Spirit and said, “I thank you, Father, Lord of heaven and earth, because you have hidden these things from the wise and the intelligent and have revealed them to infants; yes, Father, for such was your gracious will. 22 All things have been handed over to me by my Father; and no one knows who the Son is except the Father, or who the Father is except the Son and anyone to whom the Son chooses to reveal him.”
11:16 Others, to test him, kept demanding from him a sign from heaven.
12:32 Do not be afraid, little flock, for it is your Father’s good pleasure to give you the kingdom. 33 Sell your possessions, and give alms. Make purses for yourselves that do not wear out, an unfailing treasure in heaven, where no thief comes near and no moth destroys. 34 For where your treasure is, there your heart will be also.
First, God is the Lord of heaven and earth — here heaven is in contrast to and in comparison with earth. Two different places. Here heaven is the place where God has his secrets and mysteries, which the Father has made known to his Son. There’s something significant here: heaven is the place of God’s mysteries.
Third, 12:32-33 teaches that heaven is a place that is safe and a safety into which the “little flock” of Jesus will enter. It is brought into near synonymity with “kingdom” because how 12:32 and 12:33 are near parallels.