/dev folder not showing up in Finder

The /dev directory is not meant to be read and especially not written by any standard utilities. The directory contains the low level links to the raw character & block devices. The information here is not going to be recognizable to most users. There is a reason that macOS hides certain system areas from end users.

Users need to remain in their own user home folder. The user's home folder is the only area a user should be working especially modifying files. Anywhere outside of the user's home folder is considered the macOS system area and should not be touched unless the user knows what they are doing.

No insult was intended, it is just that many users decide to have a look around without knowing anything about the inner workings of macOS so they end up getting into trouble when they don't read up on these things first.

I hope you have some sort of backup for the data you have stored in the cloud since iCloud is not a replacement for a dedicated backup. Any data stored in iCloud needs to have a backup in case you accidentally delete an important file or you accidentally make an unwanted change to a file.

With a command-line tool. It's hardcoded to be invisible to regular applications on the startup disk.

If you look at it on a non-startup disk, it'll be accessible from the GUI but empty.

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Any Terminal command or utility. It can be accessed from there as normal, but not in any of the regular applications.

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