@Della:
...due to being compromised mentally/physically,...
True, but only in the sense that the President can’t discharge his duties. If you asked the left if Trump is “mentally compromised”, the answer would be ‘yes’. Does that mean he should be removed? No, because they consider anyone that doesn’t agree with them to be mentally compromised.
Also, “physically compromised” would only mean in the sense of discharging the presidential duties. After all, I don’t think you would agree that a man in a wheelchair can’t be President, right?
We have to be careful not to bring in weasel words that reduce “fitness for office” to “positions I agree with”. I’m not saying you are doing this, but the details matter.
conflicts of interest,
What do you mean here? This is too vague.
or illegal/unconstitutional actions.
No, I disagree here. Impeachment is meant to take care of this scenario, not the 25th Amendment. In other words, if the President shot a man in the face, murdered a man, you wouldn’t invoke the 25th Amendment. Rather, you would impeach.