If I understand your post correct, you have a working phone right now?
You can use the device perfectly fine with an unlocked bootloader, since I already wrote a summary of the possible downsides earlier today I’ll just link to it here.
While it is possible to exploit an unlocked bootloader, the chances of this happening are slim to none, I and many others are running around with an unlocked bootloader. And since there are quite a few reports of bricking phones after locking the bootloader with yet not exactly known causes, I’d suggest not locking the bootloader for now 