Usually if I’m gonna be outside doing exercise or labor, I’ll flip my phone around in my pocket. It’s more comfortable putting the screen against my leg, but it does indeed somehow always manage to wake up when my leg gets sweaty. So if my leg is gonna get sweaty, my phone goes in backwards instead.
There is also the alternate option of disabling certain smart lock features, so that the phone is always fully locked in your pocket. I think just the one about not fully locking if it hasn’t left your person. Humans are never fully still, so it basically keeps the phone only partially locked until the second it’s completely still for an entire second. I kind of like that feature, so when deciding between that or remembering to turn my phone around, I went with the latter, but if you are in that position alot, it might be worth it to you to disable the feature.