Now experimenting with some new sort of wire-sculpting technique (as in literal wire sculpt) and now I think of having an operator running in edit mode, that will allow the creation of mesh lines just as drawing. Though is not a choice of annotations or grease pencil since these are alternatives. I am mostly interested in real mesh vertices since there lots of powerful modifiers and operators to work with these in mesh edit mode.
For simplicity even throwing random vertices will do, I am interested to get the basic mechanism first, then the rest of the details will be figured out.
Any ideas or references to study about something similar will be a great help if you know. Most important of all is to figure out how the modal operator or the tool mode will work.