Unexpected
Well, that was an unexpected root cause.
After 4 hours of work, I finally got the latch assembly disconnected and out of the car. And as in the Gen 4 example on here, I did un-bolt the bottom window track and loosen BUT NOT REMOVE the upper nut to allow the track to pivot out of the way during this repair.
By the way, I did cheat somewhat by drilling a 3/8" hole thru the inner door sheet metal right on top of where the interior door operating link ends (but still within the border of the door panel). With that, I was able to pass thru a small screw driver and easily unlatch the plastic rod clip. Be very careful if you do this: slowly sneak up on finally breaking thru as there is a wiring harness quite nearby that could get nipped or snatched by the bit. Plus, I don't know how other people did it, but I had to remove the outer door handle again. With this out of the way, it was far easier to unlatch the lock linkage clip (while holding the plastic anti-theft shield out of the way.
Once I got the latch assembly out I realized I had purchased the wrong door lock actuators (they have three terminals for one plug, whereas mine has two separate connectors). What's crazy is that Amazon does list them (Dorman 746-655 & 746-654) fitting my car but they do not. It is a US built car and I think the passenger door is original, so I have no idea. Not impossible Amazon is wrong, I suppose.
Fortunately, it wasn't an electrical issue; it was a broken plastic linkage clip - an EXTRA broken plastic linkage clip! I think the only explanation is that it was from a prior outer door handle R&R (which I did about 4 years ago) that resulted in the clip for the operating rod falling out and eventually (about two years ago, IIRC) working its way down to the latch assembly via the anti-theft shielding and finally falling into place to block the cylinder lock linkage from moving to the unlock position. I honestly don't remember losing that clip out of the old door handle, but it really is the only explanation, given how long I've owned the car.
Anyway, thrilled that I can again unlock and open the passenger car door for my girl, as a gentleman should.