I made an account just to comment on this. I've had a modded switch for almost a year now, and have been wanting to keep backups of my games on my pc. So when I saw this, I was really excited to try it out. Now, I realize this is super new, and there are plenty of bugs to work out, but I had a pretty rough experience.
I dumped Super Mario Odyssey, threw it and the update nsp into a folder, and directed the Manager to that folder. I was using the GUI, not Console, btw. Unfortunately it didn't recognize either of my nsp's, saying the folder was empty. I did a lot to try and fix it; renaming them, moving the folder itself around, throwing in my prod.keys. Nothing changed.
Then, suddenly, as if by magic, Super Mario Odyssey showed up. I honestly can't tell you why, or how. I really didn't do anything different, just opened it up to look through the settings. In my excitement, I closed the app, deciding to go into the settings.json so I could mess around with the organization settings. Unfortunately, once I reopened the app, not only was Super Mario Odyssey gone, but it was asking me to choose a base folder again. Weirdly enough, the settings had all been reset to default. All my changes were gone.
I messed around for the better part of two hours, and the results were seemingly random. Sometimes the game was there, sometimes it wasn't, and my settings were reset on many occasions. I even noticed that if you have it set to make subfolders for each game, the Manager can't find them. That easily could just be one of the many bugs I encountered, though.
Anyways, I really hope this gets ironed out, as I'd love to store my games with a manager like this. It looks really clean, and I love the info on missing updates/dlc. Thanks for all the hard work you're putting into this, it's seriously super promising, and I can't wait to use it regularly.