This is a short feature request, and/or a call for others to post their workarounds to this same issue.
My Observable team has auto-pretty formatting off by default, as there are some cases where we find the default pretty format has made our code less readable.
However, in many cases we do still want to auto-format cells. I think it would be intuitive and convenient to have a keyboard shortcut for this kind of thing: perhaps
Alt+Enter for “Run cell and format code” or “format code in current cell”