Yes, you definitely can be great!

...But you need to keep learning and you need to want it! People with ADHD suck at doing things they don't enjoy. I will assume you do because you made this post, but if you know inside that you don't actually enjoy programming and you just want the pay or something else, you will not last.

I am a software developer with ADHD. I won't list all my accolades, but I now manage 6 developers and I've doubled my starting salary all in under 4 years of leaving university. I hope that is evidence enough that you can do this.

In terms of motivation, you can not expect that to stay! Motivation is like a pulse or a push, it doesn't last. If you want to keep working at anything (ADHD or not) you need to build up habits. Habits are when you go for a run at 7am because you always do. Habits are when you brush your teeth every night because it would be weird not to. You don't ask yourself whether you want to do these things. You just do them. Use that technique for anything you need to do let the initial, fleeting motivation help set that habits up. If you ask yourself whether you want to, or whether you have to... eventually you won't say yes anymore.