Of these three Scripture passages, only the Psalm response seems to lend itself to devotion, prayer, and Advent longing: "Justice shall flourish in his time and fullness of peace forever." One could pray on that one-liner and the rest of the psalm too, seeing in Jesus the fulfillment of all God's promises.
But I wouldn't give up so easily on mining the possible treasure one could find in the other two readings. I offer this particular angle on the Gospel passage. The lengthy genealogy lists four women all of whom are foreigners with somewhat shady characters. Tamar dressed as a temple or sacred prostitute to win Judah's favor and become the mother of his child! Rahab was indeed a prostitute who rescued Joshua's spies and helped him win victory over the Canaanites and safety for her own household! Ruth entered sacred history as a pagan who married into the chosen people, and Bathsheba's beauty tempted David to commit murder and marry her and become the father of Solomon, who late in life was himself taken up with foreign women! And this all leads to the marriage of the pregnant virgin, Mary, to Joseph! Of her is born Jesus who is called the Christ, who will indeed take away the sins of the world! Now here we have some material to ponder, to wonder at, and to pray over!
We can reflect on how God's ways, Gods actions, God's preferences are so unlike our own. God always chooses the weak to confound the strong. God lifts up the lowly and humbles the proud. God's love welcomes and includes and embraces foreigners, strangers, "enemies." God surprises us at every turn of our lives.
We even see this in the blessing of Judah by Jacob. How is it that this wayward son, this "lion's whelp," this fierce king of beasts is chosen to be the ancestor of the lamb of God who takes away the sins of the world? In grateful awe and wondering gaze, let us admire, praise, and welcome God's startling ways and ask to be freed of all those pre-conceptions, prejudices, presuppositions, and perceptions that keep us from recognizing the presence of grace and the providence of God in all the events, sufferings, and people that God brings into our world and into each of our lives. Let us especially recognize God's pattern of choosing the unlikely, the unnoticed, the unknown, the unsung folks of our world. Truly, they join together in a lowly chorus and sing with Mary: "For God has looked upon his servant in her lowliness; all generations shall call me blessed. God who is mighty has done great things for me, holy is his name; His mercy is from age to age on those who fear him." Let us sing along!