How can I permanently unhide invisible files on mac (not just make invisible files visible!)?
There are two ways that I know of to hide a file on macOS:


Start the file name with a . (period) -- this is carry over from Unix systems and the Finder still to this day honors the tradition.
Assign the hidden attribute to the file. To do this, you would use the chflags command-line program via the Terminal app.


Thus to reveal all hidden items in the Finder, one would have to do two things:


Enable in Finder viewing of items that start with a . (period). This is what you have already done.
Find all files and folders with the hidden attribute and remove the attribute with chflags nohidden. You can script this with various command-line programs or you could use something like Batchmod application do to so for you.