Without handles on that pot, that can't be the easiest thing to drain thru a strainer...
Were it me, and I were desperate for a colander, I'd get a shop to cut out a circle of stainless steel to fit the pot ( I think there is an inside lip), and drill holes in that instead. It could store in the bottom of the bag.
Is anyone using the stacking shelf containers? If so, has anyone looked for sliding lids? I found some in IG, but they all seem to be home or small-batch made. Can't find anything using the Google.
Here is a pic of one of them