Author here! Happy to answer any questions folks have.
(I would also be remiss if I didn't say that I am grateful to HN for introducing me to what was called microISVs a decade ago, "indie hacking" five years ago, and now I suppose is mostly called "building in public" / "lifestyle businesses". I was inspired to start Buttondown in no small part due to reading about Candy Japan, Appointment Reminder, et al, and learning that there was a different yet equally valid path for growing a SaaS)
(I would also be remiss if I didn't say that I am grateful to HN for introducing me to what was called microISVs a decade ago, "indie hacking" five years ago, and now I suppose is mostly called "building in public" / "lifestyle businesses". I was inspired to start Buttondown in no small part due to reading about Candy Japan, Appointment Reminder, et al, and learning that there was a different yet equally valid path for growing a SaaS)