Educate me on what this is.
As far as Pelosi being President, it is my understanding that happens only if both the Pres and VP suddenly die, removed or incapacitated.
That could happen if Biden dies tomorrow while Harris is out of the country.
Being out of the country does not qualify as being incapacitated. In the event the President died, the VP would be brought to Washington and sworn in as President. The Speaker can only become the President if there is no President or Vice President (death, resignation, or removal after impeachment).
Now think about this. What if the Vice President invokes the 25th Amendment and has the President removed, then the Vice President becomes acting President. But then what if the VP/acting-President dies? Then what? Pelosi becomes acting President. But if the removed President wants to declare his/her ability to resume office, there will be no Speaker to petition. So as long as there is no Speaker, the removed President has no way to assume office. And with no Vice President, there is no way to prevent the removed President from regaining office. And finally, if the former-Speaker/Acting-President is replaced, that person does not become Vice President, but will be out of a job.