Both Amazon.ca & Chapters-Indigo are reporting that July 19, 2022 audiobooks of the original 1927 The Tower Treasure & The House On The Cliff will be released as digital files & CD (Chapters).
https://www.amazon.ca/House-Cliff-Hardy-Boys-Book/dp/B0B2J86L5K/ref=mp_s_a_1_1?keywords=the+hardy+boys&qid=1655252643&refinements=p_lbr_books_authors_browse-bin%3AFranklin+W.+Dixon&rnid=2733778011&s=books&sr=1-1