"I replaced the screen"

Is it user-replaceable by design, or did you resort to previously undisclosed, mad phone-repair skillz?

MrsD.'s cheapo phone has had a broken screen for years, with major, multiple cracks spanning it from a single trip to the floor. I tried to persuade her to just buy a new phone (my current phone cost me 50 bucks, which is probably cheaper than getting hers repaired by a shop).

Not exactly by design, but it was available as an OEM part and enough people had dropped phones for there to be YouTube vids. I don't know about mad skillz. It's comparable to working on a laptop which I've done a bit replacing batteries, fans, drives etc.

If you're thinking about doing it, then a search in your search-engine of choice should reveal whether the part is available and whether there are instructional vids. If you can find both then it probably isn't that hard to do. The hardest part with the OnePlus 1 was being organised and brave, because it meant dismantling almost every part of the phone.