I also disagree about the VP being able to nominate a new VP.
It says Acting President, not President.
Presumably if the President were to be no longer disabled, he could be reinstated.
The president is reinstated immediately by just saying “Um, guys, I’m still here.” It then requires a 2/3 vote of BOTH HOUSES to remove him. So it’s even more difficult to do than to impeach and remove a president, because impeachment/removal requires only a majority of the House and 2/3 of the Senate.
The 25th Amendment is written the way it is to insulate it from politics, by having the President’s own VP AND Cabinet be part of the process to remove his power. Pelosi’s plan would be seen as pure politics any time the Congress and the presidency were of different parties.