人A「すげー！月のデコボコがちゃんと見える！」
人A「なんだこれ？天体望遠鏡ってこんなにすげーのか？すげーしか言えないけど、デコボコすげえ！」
I cannot completely understand the meaning of けど in this sentence, and what is the point of using it in this particular case.
けど is not for adversative conjunction in that sentence. It just shows that the preceding clause/phrase is an introduction of the main clause.
−けれど(も)
((接続助詞))
2 〔特別の意味なしに前後を結びつけて〕
あの，私ですけれど，入っていいですか
It's me. May I come in?
心配なのは分かるけれど，危ないと思いすぎているんじゃないか
While I understand your concern, I think you are exaggerating the danger.