>- Remove the data. This is much harder than it sounds. Many PDF tools won't let you change the content of a PDF, not because it isn't possible, but because you'll likely massively screw up the formatting, and the tools don't want to deal with that.

>- Replace the data. This what what all the "blackout" tools do, find "A" and replace with "🮋". This is effective and doesn't break formatting since it's a 1-to-1 replacement. The problem with "replacing" is that not every PDF tool works the same way, and some, instead, just change the foreground and background color to black; it looks nearly the same, but the power of copy-and-paste still functions.

You're making it sound way harder than it is, when both adobe acrobat and the built-in preview app on mac can both competently redact documents. I'm not aware of instances of either (or any other purpose-made redaction tools) failing. I wouldn't homebrew a python script to do my redaction either, but that doesn't mean doing redactions properly in some insurmountable task for some intern.

I would not trust either tool to adequately redact documents, though I'm sure it works under normal levels of scrutiny.

The most reliable way is to just screenshot the document or print and scan it, effectively burning it down and recreating it in a new format that has no concept of the past. This works across basically all formats, too, and against all tools.