The part about seeing the results immediately can be done easily ie via plugins in text editors like Notepad++. You have left pane with markdown text and right pane with rendered result, updated after each keystroke.
I've tried 2 different plugins, they are a bit finnicky re formatting (I do a lot of bullet points in my various todo lists and a small thing can break whole block of them) and output looks a bit different, but I still prefer them.
Heck, I often prefer reading markdown itself these days just for myself since the structure is already there and visible, I've learned to see those formatting characters as already sort of rendered formatting so not even looking into rendered pane that much.
I've tried 2 different plugins, they are a bit finnicky re formatting (I do a lot of bullet points in my various todo lists and a small thing can break whole block of them) and output looks a bit different, but I still prefer them.
Heck, I often prefer reading markdown itself these days just for myself since the structure is already there and visible, I've learned to see those formatting characters as already sort of rendered formatting so not even looking into rendered pane that much.