People interested in such solution available for other platforms may want to try TagSpaces https://www.tagspaces.org/ or TMSU https://tmsu.org/ which provide mechanisms for managing tags of arbitrary files.
Ritt can tag arbitrary files too. I like TagSpaces, but I don't think modifying the user's files, either by renaming or sidecar files, is the best approach. Ritt handles tagging purely by linking to the tagged files and so is completely non-perturbative.