Although I can use things like the .hidden file to hide files even if they don't start with a period, there doesn't seem to be any way to SHOW a file even if it does start with a period. There are certain files (not created by me) which, despite being hidden with a period at the front, I still actually access fairly frequently (eg, .ssh, .config), and I'd like to be able to see them in the normal file list without enabling "show hidden files" which also clutters my home directory with tons of other files I don't want to see. Simple options here would be to either have a .visible file that works the opposite of the .hidden file, or follow things like .gitignore syntax and allow a ! at the beginning of the line in the .hidden file to reverse it? There may already be a standard for this in other apps but I've had trouble finding any real documentation about .hidden files in general... If a preferred option is given, I can make an attempt at implementing it myself, although a pointer in the direction of what code actually implements the .hidden file logic would be handy as it's not appearing obviously searching the codebase...
I think this would add too much complexity to workflows and code. Dotfiles are hidden by convention for many, many years. Personally, I press Ctrl+H to show hidden files if I need to access them, and I press Ctrl+H again when I am done. If you do need to access hidden files/folders often, you could create a symlink to such a file/folder where the symlink is not hidden of course. But I think anything else, especially breaking a year-long convention, would be wrong. The fact that the home directory is cluttered with many dotfiles is a different issue which the XDG Base Directory Specification tries to solve. Firefox has been in the news recently for finally following that specification after 21 years. (Tough, Firefox is older than the specification, to be fair)
I'll pass this along to the Dolphin maintainers to consider. To set expectations, this may be deemed to add too much complexity for what is likely an edge case.