Nope. Not as far as I know – for both of your questions.
Also with the data you have at hand I would pick a different visualization type - e.g. a row chart or bar chart. Far easier to compare the relative size of your categories at a glance.
Yes – I know – everybody cries for pie’s (or donut’s for that matter) at first. But for most visualizations with more than just a few groups there are often better alternatives … https://www.google.com/search?q=pie+chart+controversy
I was going to suggest a stacked bar, but with only one bar. Sadly, you only get the option to stack the bars if you have mutiple values for all the groups.
Could be worth modifying the pie chart and recompiling. Depends how important it is.
That's a fair point. But I see in your second screenshot that you already found a workaround with enlarging the donut size. I searched for the word "pie" in open issues on GitHub and there's already an open one with a proposed solution to your original issue with that. You can it on GitHub if you like the solution proposed:
@AndrewMBaines yes I know! It’s a lost battle! Anyway thank you for helping to lighten up the tone of voice here. (I was getting a bit into the grumpy corner). So let’s be constructive - and have a laugh at the same time:
It’s actually not possible in Metabase either at the moment to make that row chart with relative ratios with % shown. So I’ll raise that as an enhancement request!
update: added as GitHub issue #8150: (please chime in as you see fit)
it on GitHub if you like the solution proposed:
https://eazybi.com/static/img/blog_page/posts/2016_03_01/data_visualization_pie_to_bar.gif