There are 3 kinds of pain you can experience. From talking and reading, everyone can have different experiences.
The first is when the stone is trying to exit your kidney. I've never been stabbed, but "being stabbed in the kidney" is how I describe this. It is pain you can't escape, but hydration helps. I didn't know you could vomit from pain, but you can. At lower pain levels it is more of a painful twinge. This pain can be constant or "wavy" - I could be crippled for hours or perfectly fine and then switch.
The second is while the stone works its way into the ureathra (I'm probably getting all the locations wrong, but the symptoms are the point). This feels like a UTI - a burning itch and the constant feeling (but not reality) of having to urinate. Despite the low pain levels, I hated this phase the most.
The third is actually passing the stone. This can be a quick sharp pain, no pain at all, or an agonizing drawn out experience. The stones vary in sharpness (stones can have different textures, mine that look managed to catch were clumps of crystal grains and some grit-like mortar, so degrees of effective sharpness also vary. ) "coral" is not a bad description of the material.
Size matters a lot - apparently stones are very normal and people pass tiny ones all the time without knowing. Unfortunately, if one stuck around in the kidneys to get larger and got loose (I have no real idea of what that means in terms of tissues) it can hurt. More unfortunately, the resulting inflamation can trigger more, so it not uncommon to get waves of stones. With a few days or a couple of weeks in between.
Time to pass, indeed, time in each of the three stages can vary. I've been fortunate that most of mine pass in a few days, with the worst taking 3 weeks with an ultrasound attempt to break it up after the first 2 weeks.
I feel fortunate that, despite the intense kidney pain that not everyone gets, I've had only minimal discomfort in actually passing the stones.
One important note: hydration is key to pain reduction. Chug water constantly. My biggest issues were always 2-4 am, when I'd been asleep and not drinking for a few hours - by the time the pain woke me up, I had a few bad hours ahead of me.
There is a lot of folk medicine out there, as well as random advice about diet, including from doctors, but I've not found any convincing nor consistent recommendations beyond water hydration.
Medical treatment is normally to just hydrate and wait it out. Some docs will want an xray to see if they can see if they can see it, but the resolution isn't usually good enough for that to mean anything. A GOOD ct scan can see it, but if are in the US don't bother until a specialist requests it or the specialist will just want it done by them. If the stone is too large to pass on it's own, or taking too long (your call, but probably at 2 weeks) they can hit it with ultrasound to try and break it up into smaller pieces. They may not get it though, so this can take more than one visit.
Lastly, I want to say that debates about pregnancy be kidney pain are stupid. Every experience and every person is different, so let's just agree on "this is big pain" and "big pain is bad" and leave it there. So much of what I found online was just this debate over and over again.
The ultrasonics can break the larger stones but this effects a certain volume. So if you miss or the stone is smaller, then the ultrasonics can damage the surrounding kidney tissue. I had other stones which were confirmed by X-ray but too small to target effectively.
The advice I got from a number of medics, drink > 2 litres of liquid per day (Any liquid). If the urine is still coloured after the first piss of the day, then drink some more. Other than that, there was no confirmed list of things to avoid.
The first time was the worse as you don’t know WTF is going on. After that, I keep my hydration up, carry good painkillers and know when to get to hospital if required.
I agree that the pain debate is pointless, we’re all different.