It's possible, but as I mentioned in another comment, building this as an extension has some added benefits [1].
> that way I don't have to bloat the browser's start-up time and don't have to "worry" about this extension spying on other websites, even though I realize it's unlikely
No need to worry about that, as it's limited by the permissions specified in the extension manifiest. So this extension can only access news.ycombinator.com and extensionpay.com to facilitate the Pro upgrade.
I wish this were more of an SPA with an account system/db of it's own, I'd even pay for a subscription (small one). I'd basically like there to be a mobile app and desktop version that no matter where I read an article, it's marked read. I use materialize and hckrnews now, if both of these could keep track of the same bookmarks, visited links, and maybe allow note taking or creating groups of saved things, that'd be awesome. Also notifications and a messaging system like reddit has would be cool...in fact I just want a redditized HN experience lol.
> that way I don't have to bloat the browser's start-up time and don't have to "worry" about this extension spying on other websites, even though I realize it's unlikely
No need to worry about that, as it's limited by the permissions specified in the extension manifiest. So this extension can only access news.ycombinator.com and extensionpay.com to facilitate the Pro upgrade.
[1] https://news.ycombinator.com/item?id=32769145