Ouch for those who have damaged cameras while riding!
I have experimented with several. For a total weight-weenie experience for the steepest climbs, I often brought some kind of early 2000s Canon Elph, even a few years ago, because my 'smart' phones were typically so cheap that their snapshot capability is not much better-- and if I'm running GPS, sometimes using the camera would confuse my phone, and I'd lose signal in places where signal was weak when I switched to the camera app. Strava was terrible for that-- it would crash and lost all my stats whenever I took a photo, so I got rid of Strava... and the phone.
I have also used an older Canon S90, which I found very serviceable, way better than the Elph, sometimes better than the camera on my Samsung A-15, but it depends. The S90 seems to be more reliable in terms of fewer missed and out-of-focus shots, but the A15 definitely has the edge with dynamic range, which is the achilles hell of the S90, an otherwise amazing camera in a tiny, very lightweight form factor.
On other rides, even fairly long ones, if I'm not likely to dump the bike, for a while I was using a Fuji X-A5, though the holster case was bulky with the zoom kit lens. So I got a 39mm lens for it, and it fits in a very small case... but unfortunately, though the Fuji takes great pictures, I have discovered that touch screen, particularly as it's implemented on this series of cameras, is a hard no-go for me. Invariably, I'll hit the wrong spot on the screen, and put the camera into some Weirdo Mode where everything is overexposed, or in cartoon emulation, and while the A5 is wonderfully small for a mirrorless, the form factor makes it too hard to handle, which worsens the touch-screen issues. It's slippery and the thumb rest is way too small. For a while, I tried to train myself to avoid Weirdo Mode, but eventually gave up. After a steep climb, when my hands might be slick with sweat and trembling from exertion + osteoarthritis and vibration from the bars? I WILL be clumsy with the camera. The other issue is, the 39mm just isn't quite wide enough with a cropped sensor.
Eventually, I bit the bullet and got a Canon R100. It has the same sensor size as the A15, and NO touchscreen-- this is a feature, not a bug for me-- but is, unfortunately, bigger. I do have a case that will accommodate the kit zoom lens, but it's enormous, and sticks too far off my belt-- fine for hiking, not great for biking. I got a 50mm lens for it, though... I don't know why, I think I was seduced by being able to go down to f1.8. Anyway, you live and learn, on a cropped sensor, I just don't have much use for a cropped nifty fifty, it's almost too tight even for shooting bands in dark clubs.
Enter the Cannon RF 28mm, which is super compact and fits in a case that's about the same size as the A15's case with the kit lens. So far so good for eBiking-- I'm now using it the Ken Rockwell way = no lens cap, just a clear filter that I'll replace if it cracks or breaks. And yes, I realize there are some kinds of impact the filter won't protect the lens from, it's maybe 70% as protective. The padding in the case-- a Chinese clone of the smallest Mirrorless Mover, though it's slightly wider, the Mirrorless Mover is too tight a fit-- seems entirely sufficient... but the belt loop is not quite robust enough. Solution is a very large aluminum caribiner (!) (yeah, I know) that is threaded through the loop for the neck strap, which is much better secured, and a second belt loop. The biner is really featherweight, it's lighter than the case, and theoretically, if the belt loop rips, the biner will hold the camera to a second belt loop, where it can dangle until I get home.
The thing is, for all eMTB situations, I need to be able to draw the camera and shoot fast with bad hands, particularly for wildlife. (Or shooting deserted streets covered with razor wire and graffiti with homeless dudes zoned out on tranq lurking nearby.) Futzing with a lens cap, or having the camera hang up in the case when I pull it out, is a problem. The R100 is way larger and heavier than a mobile phone, but far easier to grip even with the arthritis, and I have a monster wrist strap for it.
This also eliminates another issue I've feared-- taking photos with my phone, which is hard for me to hold even in a case, and then dropping it off a cliff, losing GPS, and having to bird-dog it home. There are a few trails I ride, though not many, where it is REALLY hard to remember which fork in the trail takes you down the mountain the intermediate or novice way vs. the crazy-pants black diamond route I can't even walk the bike down.