Hi,
I have dealing a bit with the code of QIIME2 as I am writing the second edition of my Bioinformatics Book and will include some content on it.
I have to say that I am amazingly well impressed by the quality of it all.
I have read and produced lots of Python code over the years and QIIME2 is one of the Top 5 projects in terms of code quality.
Really really well impressed.
Congratulations