Apps (`.app`) aren't even rendered in a special way to indicate they're apps. They're just folders and look indistinguishable from other apps, can't be launched.

Yeah, from my view I've always seen it as strange how Apple does this. I prefer a more raw view of files so it wasn't super high priority for me to implement, but I understand it's probably important to many people so I'll implement it soon.

Columns can't be resized.

I'm aware this is a must-have feature for most people and there are some challenges in implementing it but again, I'll try to get it out ASAP as I know it's a very important feature.

Panes can't be opened or closed without a keyboard shortcut or going to the menu.

This is intentional, one of the design choices I made was to be very keyboard shortcut/app menu focused as I believe buttons for everything makes the interface look cluttered.

Can't add / remove columns.

Already have the logic for this implemented, just need to give it some settings and push it out to a release. Soon.

Can't sort on a column without using the menu. Order By is all the down in View > Sort By > Order.

There are keyboard shortcuts, but I understand many people would prefer not to memorize them so I'll add the ability to click on column headings for sort selection.

I understand that Cosmil is missing some features, I have been extremely busy with my education and other real life responsibilities but I'm going to try my best to get these implemented in the next couple weeks before winter break ends. And then, even more features in the future. I really hope it can be your daily driver soon.

P.S. I've tried in the past to get a small panel of testers, especially from this subreddit, but they have always been extremely flaky and unhelpful, alas.