One concern I have with this aspect of it is that, depending on the condition you are suffering from, it’s possible you will not physically be able to take the drug yourself.
So, the dilemma: take it today while you can (and cut your life short a little earlier than you might choose to), or wait a few weeks and risk no longer being able to get the pills out and into your own mouth.
Allowing someone else to give you the pills (or whatever form it takes) allows you to delay the point of no return - on the other hand, it puts someone else into the position of administering the lethal dose. However supportive that person might be, it’s tough (and opens up other cans of worms).
My mother had lung cancer. She had a lung removed, they thought they got it all, and the protocol was to NOT give chemo at the stage she was believed to be.
A year later, it came back. She went through chemo and radiation which basically did nothing. It ultimately killed her, just before Christmas. She was in the hospital, and was adamant about not wanting another bronchoscopy and some other procedures. Despite that, my one brother (asshole) wanted to fight to take her medical POA away from the other brothers, so he could force her to go through those procedures. Fortunately he never pursued this - despite his clearly loving Mom more than the rest of us murderous goons, he left town after 2 days, before her death. Had she lingered much longer, the battle might have gotten ugly.
The hospital gave her high doses of morphine to relieve her breathing distress - this may or may not have hastened her final moments (though not by much).
In the case of the OP’s father, at this point there’s little they can do. It sounds like he’s not “there” enough mentally to make a binding decision to end his life even in those states which permit it. it sounds like he’s got nothing urgent enough that would take him swiftly if left untreated, so a DNR order won’t do much at this stage. And you can’t exactly quit feeding him at this point.
Some things to consider, when updating your own POAs: I read an article years back from a person whose father had a pacemaker or internal defibrillator - then developed Alzheimer’s. Turning off the device would have allowed him to slip away faster, but the doctors weren’t exactly eager to do that. Ultimately they went before a judge and got permission to do so.
So, when I updated my own medical POA a couple years back, I made sure to document things like that. As in, if I’m mentally not there, things like that may be avoided (or turned off if in place). Routine screenings may be avoided - why put me through, say, a mammogram or colonoscopy, when there’s little reason to extend my life. I also put in a clause to the effect of if I’m mentally OK, but physically disabled (e.g. paralyzed, ALS or whatever), I may refuse food/water/etc., and this was to serve as documentation that I had put thought into that well before the issue arose.