As for data labels, you’ll need to add another mark to the spec (this time of type = text). The way forward with you code sample didn’t fall out easily; I’d probably start with a standard line mark for [Sales], add a standard line mark for [Target], then add the text marks before looking into the repeat block (I’ve very little experience with the repeat syntax.). I’d review the examples on the Vega-Lite website for more info.
So, while I was able to get the data labels showing, they can overlap and reading them can be challenging; not sure if this is what you were going for, and even though this thread is solved, I decided to post anyway for documentation and in case it is of interest.
Greg eDNA Forum - Deneb Y-axis off datalabels on.pbix (1.7 MB) https://vis-au.github.io/vl/