What could I be doing better?

I don't have any thoughts, but getting 160 subscribers in a month is pretty good tbh!
Keep it up 👌👌👌

I liked it. Probably the only thing I'd like to see more of is the person's background was a bit impersonal. Felt like a CV's personal statement, though their quotes in the same section were good and interesting. You could listen to How I built This or My first million to try pick up personal/background questions to deploy.

One other thing would be in the timeline at the end, could it be made more specific? Have the in depth marketing section earlier and then reference it in the timeline. Mainly I'm just wondering were the track tunes first 5k downloads w/o any marketing, does it include the app feature (did they get that feature in the end?)

Sub'd anyway. You have a line to enter your email addrss and then launch a pop up instead. I closed the popup out of habit to get to the input line I had clicked, not realising the input line was a dummy and I needed to use the pop up. Change the dummy input to a button or make it work as the actual email input as it's confusing

Increasing sign ups is going to be done by your marketing anyway. See this other HN post to see how this newsletter did it https://ideaeconomy.net/my-first-2000-subscribers/

I read through and I noticed you publish pretty strictly 1x a week. While I definitely think a regular publishing schedule is important, I also think its more beneficial to wait until you have something great than publish just for the sake of it. You can smooth this out a bit by scheduling things ahead of time in a queue and using that when things dry up.