Taking your three queries together, you may find the working timetables on this site of interest:-
They may take a bit of understanding at first but they do indicate where buses stand (park in everyday terminology) and give times at each of the major timing points (not at all stops). It is however quite complicated to work out which working timetables relate to Covid as the special schedules have been implemented in different ways at different times.In particular, the practice for some weeks was to associate the specials with the existing “service change number”, thus they might be listed under a much earlier date.
This page on a different website
gives a summary of what is thought to have operated when and gives links to timetables in Excel form (which I know are largely derived from the working timetables, so again not all stops) but I doubt that it is the whole story. To be honest I doubt that will ever be known.
This particular post reminds me of my statistician’s strategy when I was working - always find out what the client is trying to achieve, as there may be better ways of doing it - or someone else may have already done something very similar. For example, if Covid is the point, I doubt you will do much better than has already been done. If that is not the point, then what are you trying to investigate? Also, are you trying to investigate all routes or just a handful?
As well as Covid, the period you are asking about would also include seasonal variations around Christmas and the New Year.
Full lists of stops supposedly served over the period may be easier to provide, particularly if it is just for
one or two routes. They are present in another source, generally updated weekly, in XML form. Of course stops are sometimes closed, say because of a diversion. These may or may not be picked up in TfL’s systems and sometimes (whisper it quietly) what is in supposedly related TfL sources is just plain inconsistent! I have a post from a few weeks back about Bow Common Lane which illustrated this.
Hope that is of some help.