Is there a way of using bitcoin core gui in order to check if you know/correct about your wallet.dat passphrase by typing it only once?
I know you can change the passphrase, but I want to keep it and not by typing it 3 times (The other two as the 'new' passphrase).
I'm aware it might be considered a bit of an odd question, but when security is so paramount, this could matter IMO.
Yes, open the command console inside the GUI and type
walletpassphrase "your password" 1
This will only succeed if the password is correct.
If you have multiple wallets, make sure you have selected the correct wallet at the top of the console. The console only works on one wallet at a time.
If you prefer the characters not to show on the screen, then instead of doing what @meshcollider wrote, you can begin a send process by inserting an address (Use one of yours, for safety).
Then write an amount that is BIGGER than whatever you have in the entire wallet (So it won't be sent no matter what), then try to send it. It will ask for your password.
If you give the right one, it will inform you that you can't send (You don't have sufficient amount), if you enter the wrong password, it will tell you that you inserted the wrong password.
