I'm sorry, I might have been misinterpreting, could I you explain what you mean by actual characters? Even VSCode's minimap draws some shapes, but they're too small to discern any characters.
In VSCode it actually draws the font with very small size. It might look better on larger resolution displays. You can also increase the size with "editor.minimap.scale": 4
VS Code gives you a choice between actual characters and coloured blocks. Actual characters might or might not be discernable, it depends on how large you set your minimap. I personally make mine quite small, so there's no value to actual characters, but if I make it larger, I can make out enough of them to see additional structure.