Your 19.4 and 26.4 have the same finish as your 43. The old gen2 and gen3 finishes were tough. The gen4 finish is usually all scarfed up, out of the box. Not a fan
Kind of an absolute statement, I have various Gen 3 & 4 pistols with different finishes both "frying pan" and the newer less durable "gray" finish. I also have earlier Gen 2 and 2.5 models that show significant wear to the "parkerized" looking finish. Even so, in all cases the metal underneath has been fine, it is my understanding that it is due to the ferritic nitrocarburizing (Tenifer/Melonite) treatment underneath the finish.
The late 2012 19.4 & 26.4 pistols mentioned in my previous post do seem exceptionally delicate, and maybe it is just my imagination that my 2016 G43 shows little to no wear after ~1.5 years of use, while they started to show wear in mere months. Then again, it is also possible that somewhere along the way Glock tuned the finish or changed suppliers, and it is actually wearing better.
I will agree that the "frying pan" finish is my favorite Glock finish, and it does seem to show little to no wear over a very long time.
I guess I've just been lucky, as I don't recall any of my "post frying pan" & "pre nDLC" Glocks being "all scarfed up" right out of the box.
My only experience with NP3/NP3+ is on an older HK P7. I don't know that I'd consider it super durable, but it seems about as durable as any other electroless nickel finish, with a slicker feel to it. It's OK, but I'm not wild about it, as I tend to prefer black/grey over "white" guns.
Since you seem to want to refinish a G-43 before it shows any wear, and you seem to be interested in the Gen 5 nDLC, have you considered ION bond DLC?