Been impossible to unhide my OEM in order to install lineage

I would suggest you not to use KingRoot because it might not work reliably and will cause problems. Another thing is that sometimes carriers or manufacturers lock OEM unlocking feature in Developers options and there might not be a straightforward way to unlock it. You can try by searching for specific instructions for your phone model and carrier online.

Firstly, attempting to unlock your bootloader through methods like KingRoot might not always work reliably and could potentially cause issues with your device. It's crucial to be cautious with third-party rooting tools as they can sometimes lead to unexpected consequences.

Regarding unlocking the OEM bootloader on your Samsung S10, there are a few steps you should follow:

Enable Developer Options: Go to Settings > About Phone and tap on the Build Number multiple times until you see a message saying "You are now a developer!"

Enable OEM Unlocking: After enabling Developer Options, go back to the main Settings menu, then navigate to Developer Options. Look for the option labeled "OEM unlocking" and toggle it on. You may need to enter your PIN or password to confirm.

Disable Factory Reset Protection (FRP): Make sure to remove any Google accounts from your device and disable FRP before attempting to unlock the bootloader. This can be done in the Settings under Accounts.

Unlock Bootloader via Fastboot: Connect your device to your computer via USB and boot it into Fastboot mode. You can usually do this by powering off your device, then holding down specific key combinations (often Volume Down + Power) while powering it on. Once in Fastboot mode, use the appropriate fastboot command to unlock the bootloader. The command may vary depending on your device and manufacturer.

Remember, unlocking the bootloader will wipe all data on your device, so make sure to back up any important files beforehand. Additionally, be aware that unlocking the bootloader may void your warranty and could potentially brick your device if not done correctly.

If you encounter any specific errors or difficulties during these steps, feel free to ask for further assistance, and the community will be happy to help troubleshoot.