Check WorldCat.org. Several university libraries with strong graphic novel collections purchased the Act I comic. The Library of Congress has a copy. The New York Public Library has a copy. If you live in a major city, interlibrary loan is your friend. You can read the physical book for the cost of gas money.
There is persistent rumor in the fan subreddit (r/TheDearHunter) that Casey is working on a massive graphic novel collection. If and when that drops, buying it new will likely include a digital code for a free DRM-free PDF. Until then, the "free" versions are either a Patreon subscription away or a YouTube search away. the dear hunter act 1 comic free
If you are trying to track down a physical "paper" copy, be aware that these are often considered collector's items: Check WorldCat