And I should report back about the above sock gadget.
Having tried it, I'm now having a lot of sympathy for @GN637 's mother who declines to use one.
This is an object where the spec looks incredibly simple, but is in fact incrediby complicated.
In its original form, this gadget needs at least three strong hands to load a sock onto it.
So I tried creasing longitudinal folds into it (stood on it). This meant the hard plastic was too firmly folded. I couldn't get my toes into the (now barely existent) opening without intervention, and even when I did, the gadget gripped my foot like death, barely moving as I yanked on the pulling-tapes and gouging my ankle with the full length as it passed. It was very painful, and I don't have pain-ridden feet in the first place.
So I slit the gadget open and started modifying. My current (fairly successful) design has the following elements.
The hard plastic remains at the top and in the central tongue - forming a T-shape with a fairly rigid cuff at the top. This makes the gadget present a decent-sized opening even when a sock has been loaded. The firm central tongue means it easily goes all the way into the sock without crumpling.
In the two side tongues I have replaced the hard plastic with something softer (milk carton plastic). I have also, after some regrettable crumpling incidents, given these their own reinforced rims with some springy steel wire. This means the side tongues now fold easily onto the rigid tongue, but keep their length, while the sock is being loaded.
As I push my foot in, the soft tongues open easily and follow the contours of foot, heel and calf.
I can even use the gadget with long socks, although a bit of hand-finishing may be required on the calves.
So, this might not be too useful for someone with painful feet, who has to avoid any pressure at all at the insertion stage. But it's a win for me as my problem is reaching my feet safely.