On macOS my daily driver is Nimble Commander (https://magnumbytes.com/). Super fast, powerful and inspired by Total Commander. It used to be paid but now is free and open source so give it a try. It deserves to be better known.
There was this tech [1] making rounds on HN a while back. Made a big impression on me and it's by the company that co-created the World of Goo 2. I wonder if it was used to make the game.
Nebula was the tech that I watched very closely and it inspired me a lot. It was back in the ancient year of 2000, if I remember correctly, when our game was being published by CDV and I just learned about Project Nomads, based on Nebula. Beautiful engine and I loved the clean, simple and extensible architecture.
I would love to have such tech nowadays, but focused on 2D/light-3D mobile games :)
Yes, Nimble Commander is wonderful. The developer took a lot of care and created a powerful and very fast tool. As a long time user of Total Commander on Windows I'd be crying sad tears if I had to limit myself to the basics that Finder provides on macOS.
Indeed, Teal looks like it has the right brains behind it (author was involved with several earlier attempts at typed Lua) and is actively maintained. I'm personally watching it for future game development usage.
Oh yes! Notes failing to sync after iOS 13 update is something that happened to me too. And apparently other people as well, as posted on Apple's forums: https://discussions.apple.com/thread/250684880
It seems like it's won't be working on Safari for much longer. Info from 2 days ago "I can confirm that on macOS Catalina Developer Beta 1, uBlock Origin is completely removed as it is not using the MAS distribution method."
Src: https://github.com/el1t/uBlock-Safari/issues/151
I've been using Nimble Commander for a while now. Snappy, similar to Total Commander on Windows and I love it. The developer recently made it open source and published the code on GitHub here: https://github.com/mikekazakov/nimble-commander
I'm not sure if that's the kind of open source you were looking for, but may be worth checking out.
After a few years on GitLab I moved to GitHub for these very reasons. GitLab's UI was messy and it was slow to display (as in input lag and low FPS on my reasonably powered desktop PC).
On Windows I've been using Total Commander for 15 years or more. There's nothing like it on Mac, and I've tried them all. But there's this new app, Files (http://filesmanager.info/), which is being actively developed and gaining features fast. I've been using it for some time now I'm liking it more and more. The developer behind it is very responsive and skilled and it seems to be going in a great direction. There's hope for OS X! :)