I always liked the Classic macOS way for using "File Type" and "File Creator" meta data. File extensions were not used at the operating system level, but were useful for cross-platform sharing or as away to organize file.

The file icon would be assigned by the "Creator" Application. Double-clicking the file would cause it to be opened by the "Creator". You could choose to open a file with anything that advertised that it could work with a "File Type". There were utilities to change the "File Creator".