You cannot unlock the phone without the passcode.
You could unlock it on the command-line using ADB, but you'll still need the passcode. If you learn java or kotlin, you can create a front-end for ADB, but that would be useless since the passcode is still required.
Now if you want to develope android apps then you have to choose between java or kotlin and only you can make that decision. I develope with java, but I learned it long before kotlin existed.
If you're serious about this, install Android Studio for app developement and google some tutorials and dive right in. You can also find my page and github in my profile where there are some tutorials.
Good luck.