I want to find an tool that would let me assign comments/notes to (any) files/folders. Preferably it can integrate itself to the right click menu and isn't janky (for example, if it creates a new file that I need to keep together with the original file, no thanks). Is there such an app that would allow me to Right Click->Notes and write down a few things about the file? I dont want it to make a separate file or clutter anything. If it is searchable through windows, would be amazing.
NTFS the Windows file-system has the ability to store multiple "alternate data streams" with each file. Effectively a list of files that are coupled to a regular file and that don't get lost as long as you copy/move the file using Windows tools that are alternate data stream aware.
There is a shell-extension named "File Metadata" that uses alternate data streams to store and edit notes and other meta data:
I have not tried it myself, but it seems to be exactly what you are looking for (at least for files).