Pelosi would not be VP. She has a better chance of being POTUS,at least for a time. With Biden gone Pelosi while next in line after Harris still remains Speaker. VP is replaced by the process of the 25th Amendment. No way Pelosi wins that.
However if the election is contested and the House and Senate refuse or are not able to certify the results by 1/20/21 then the Speaker becomes acting POTUS until results are certified.
Now here’s a weird part Root did not consider. The Speaker need not be a sitting member of the House. Can you say Pres Hillary Rodham Clinton.
You raise an interesting point.
It is obvious that after January 20, an "Acting President" Pelosi could cause all manner of mischief and you give us an example.
Although it makes little difference, I think it perhaps more likely Clinton would be installed as president not via the Succession Act but rather by determination in the House.
Perhaps even more likely, and much cleaner, is that Clinton formally replaces Biden prior to the election and it is the Electors that vote him into office. Assuming, of course, the D's carry the day.