Also, ‘gaining knowledge’ isn’t usually considered ‘exciting’. Natural might be something like: Whatever the result, you’ll feel satisfied to /have added/add/ to your knowledge and understanding.

You have written a subordinate noun clause, not a sentence. If you want it to become a sentence, you need to choose a subject and a verb. Every sentence needs a subject and a verb. Do you want to be the subject of your sentence to be "excitement" or "you"? Do you want the verb to be "feel", "is", or "gain"? All choices are possible. Once you make those choices, you can create a sentence.

"Whatever the result" makes sense in its own. It would, however, sound better at the end of the sentence as it would provide emphasis. The sentence would need rewriting because you introduce "the excitement", but don't link it to anything. Suggestion - "The excitement comes from knowing you've gained great knowledge and understanding, whatever the result"