So if you lost your mobile or hardware wallet on the street, you would have no problem with someone breaking in to it and emptying your wallets? How is that any different to emptying out a paper wallet you found which does not belong to you? Sure, OP is highly unlikely to get caught, but that hardly makes it morally OK.
But they are all locked and have security protection and passphrases, so they wouldn't be able to empty out anything, and you shouldn't carry your hardware wallet on beach anyway.
Few years ago I lost/forgot a photo camera in beach, and I never reported it as stolen because I lost it and it's my fault, nobody came and took it from me with a knife.
I am not going to put guilt on someone else for doing something wrong, when I was simply careless.
So hacking a hardware wallet is theft, but stealing a paper wallet isn't? Why?
Finding a paper wallet, not stealing.
There is a big difference.
If you think that any thing someone found was stolen in the world, than we are living in world that stole 99% of things and land from other people.
It's not the same if I found a piece of land nobody is using, and if I kill someone and take away land from him.
To conclude, I would personally try to find original owner of paper wallet.
After reasonable amount of time I would give one part to charity or poor people, and I would just stake rest for future.