I've heard that the Ariza"l was a talmid of the Ridvaz. I am wondering if it is the same person who authored the Shu"t HaRidvaz as I find that interesting since he seems to be someone that devoted his life to niglah rather than to nistar?
Indeed, this is the same person. The entry for "David ben Solomon ibn Zimra (Radbaz)" in The Responsa Literature states:
He conducted a large yeshiba and many famous scholars were his pupils. The great talmudic author, Bezalel Ashkenazi, was one of them; and Isaac Luria, the world-famous kabbalist, was another.
As for your impression about devoting his life to niglah rather than nistar, the following is also stated there:
He wrote many works, commentaries on Maimonides, rules of talmudic interpretation, kabbalistic commentaries; but, above all, he was a great respondent. Questions came to him from all over the world.
Thus, he did engage in nistar as well, but he couldn't ignore all the questions he was receiving to focus solely on nistar.
Similarly, in Chapter Seven of Theology in the Responsa we find the following statements about Radbaz:
Next to Adret, the most prolific writer of Responsa in the history of that literature is R. David Ibn Abi Zimra (1479-1573), known, after the initial letters of his name, as Radbaz.
In addition to his profound mastery of the Talmud and the legal literature, he was a renowned Kabbalist.
However, this personage should not be confused with R. Yaakov Dovid Wilovsky, who is referred to by the acronym Ridvaz or Ridbaz. Indeed, this is explicitly cautioned on the latter's Wikipedia page:
Not to be confused with Rabbi David ben Solomon ibn Abi Zimra, known as the Radvaz.