Convert your friends over to Signal. Let Snapchat harvest somebody else's personal data.

Unfortunately, what you are asking can really only be done on a rooted device and, to my knowledge, Snapchat has root detection which will prevent it from working. There are potentially some 3rd party apps you could use, but those run the risk of deactivating your account

I really want to know that for another app for a different permission.

It would be good if we can "trick" an app to think it has a permission and stop bothering us.

SnapMod has this feature. You can use it with lspatch if you are not rooted.

If you're on Android 12 or higher with a supported device, you could disable camera access with a quick settings toggle. If the camera is disabled, any app using the camera just gets a black image. (It does cause a popup asking if you want to unblock the camera, but you can just hit cancel.)

If you really must use Snapchat, there are hardware camera covers you can buy for your phone.

I just tried revoking the camera permission on my Snapchat app. There's a nag to re-enable it on the main screen, but the navbar at the bottom still lets me access my chats and view snaps from friends.

Is it not the same for you? I'm running version 12.38.0.45 on Android 10.