Welcome to the forum, @Edy2183!
There are a number of different approaches you could take, some of which have been discussed here already. A quick search of the forum will often save you a little time waiting for a response 
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The qiime tools export command can be used to grab the data from any .qza or .qzv file. Hereās a good discussion of using that tool to get Kruskal-Wallis data. Thereās more on that in the Exporting Data Tutorial.
All QIIME 2 artifacts and visualizations are, fundamentally, just zipped archives. You could also unzip the viz youāre working with, and take a look at the files in the data folder.
Finally, if you look closely at your visualization using qiime tools view faith-grpup-significance.qzv, or by opening it at view.qiime2.org, youāll notice a ādownload csvā link, that will allow you download the data for pairwise comparisons.
Chris