The WIP commits I initially recorded also don't necessarily existed as such in my file system and often don't really work completely, so I don't know why the commit after a rebase is any more a lie then the commit before the rebase.

The "honest" historical record of when I decided to use "git commit" while working on something is 100% useless for anyone but me (for me it's 90% useless).

git tracks revisions, not history of file changes.

You put past failed implementation in comments? That sounds like a nightmare. I rather only include a short description in the comment that can then link to the older implementation if necessary.