A duo is a lovely smaller alternative to a quartet or trio. For modern pop songs, it’s a great idea to pair the violin or cello with a chordal instrument such as a guitar or keyboard. The rhythms and harmonies will bring the performance closer to the sound of the original recording. You can also try a saxophone for a cool, modern, jazzy sound.
A violin and cello together sound classical and beautiful but may not be the best choice for hip-hop or rock music.
For Canon in D, any duo will be beautiful!