So is there somewhere I can see what exactly I'd be buying? $1 a month is well within my "definitely worth convenience" margin for migrating my static blog off Github pages, but I can't tell what I'd actually be buying / what the final product would look like?
That lowest plan lets you connect a custom domain and publish to Read.Write.as -- there isn't much more to it that isn't already included in the free plan.
If you want to try out everything on Pro, though, let me know your username [0] and I'll get you on a trial.