Thanks, @DEV_Scribbles!
I managed to get 8 + 8 working and was able to write a small addition to it to change headers (prepended, as you kindly say, by #h/…).
In fact all I want to be able to do - and I do appreciate that Markdown doesn’t really/officially support this kind of formatting, although I hope Obsidian might - is change the colour of single words, phrases, lines of body text (not headers - which is why I can’t really use (a variation on) #h) so that they stand out in a way that merely bolding and italicizing doesn’t.
I’m not fixated on orange, I promise; I see that 8 + 8 uses a multitude of other colours. My own note-taking convention ever since I began to use TextEdit (which I am now abandoning in favor of Obsidian) is that orange jumps out at the reader; for me it means: “go back and check this”/“This hasn’t been (fact-) checked”/“This may be wrong or incomplete”.
Once I have corrected/completed/verified this text, in TextEdit I simply select it and change it back to black.
I’m looking for something similar - albeit even, perhaps, only in Preview mode - in Obsidian. For any segment of body text.