The rule of Jesus is not limited to simply all nations. It is that and so much more - the entire universe.
Murray Harris: When believers sing or recite the confession ‘Jesus is Lord’, we are affirming his absolute supremacy, not only over the physical and moral universe (Matt. 28:18; 1 Pet. 3:22), and not only over human history (Rom. 9:5), not only over all human beings (Acts 10:36; Rom. 10:12), whether living or dead (Rom. 14:9), not only over the church (Eph. 1:22), but also over our own lives as his willing slaves (Slave of Christ: A New Testament Metaphor for Total Devotion to Christ, page 90).
This demonstrates He is Omnipotent/Almighty. Not surprisingly Christ is worshiped in praise of His “power” (Revelation 5:12), because just like the Father (cf. Revelation 4:11) it is an attribute they each possess. If Christ was not the Almighty then He would not be praised for possessing this attribute.
TDNT: In 5:12f. the angelic choirs extol the omnipotence of the Lamb in a seven-membered doxology (8:178, timē, J. Schneider).