I don’t think so. The law is that congress meets jointly on Jan 6 for the purpose of counting the electoral votes. And also it is a matter of the constitution that their terms are over on Jan. 3. So it would not be the current House/Senate.
You are right, if elections are invalidated which I doubt, then Senate would be appointed by Governors but the House would be vacant till special elections. Shouldn’t effect the President, but considering the makeup of the Senate, we could get Harris.