My car has more software bugs than my hardware wallet. And the HW is a cheap one.

I get your point, but you're not entirely right.
* The good HW by your logic will be rather expensive (plus expensive compared to the competition) and grandma' won't understand why she needs that.
* It won't matter the HW is great and friendly if there's no nice and friendly companion software wallet. I think that first step should be grandma' friendly software wallets.

Nowadays one (new?) trend is to make a NFC card (with no screen) as HW. And the companion wallet handles it all. It's not safe enough by my standards, but I think that it's the closest we have now to grandma' friendly HWs. And some are cheap too.