As someone who is just breaking into the hobby, I would like to state a little bit of a rookie perspective that may be a little heavy on the anecdotal side. Please don't take this too much as a rant, even though it kind of is....
As I am going through things trying to get started, I find there are also a lot of questions that are kind of left unanswered or not easy to find an answer to. I will try and reply to your questions in a way that somewhat illustrates this:
• Where do you currently go for aquascape inspiration — Instagram, YouTube, forums, contest archives?
Currently I mostly get inspiration for some things from YouTube, forums, and most of all things around me.
• Does that already fully scratch the itch, or is there something missing (context, explanation, curation vs. just a feed)?
No this does not fully scratch the itch.
One of the issues run into often enough, I find inspiration from multiple places, or from somewhere unrelated to aquascaping. What is the resource to be able to blend these all together?
With the build I am hoping to actually have started in the next month is going to be inspired a lot by the PNW and what I grew up with. I watched this
video of Homma giving a workshop at Green Aqua. He found the inspiration for the layout from going through the nearby woods and kind of just knew what plants to use for what. I struggle with this so resort to searching here, google, or reddit. That even has issues since when I look at a plant in one scape it may look completely different in another. I don't know what causes the difference in appearance. Is it different variations of the plants? Is it related to growing conditions (low-tech, high-tech, light, etc)? How do I change conditions to make it do what I want?
• Would a smaller, curated site/newsletter add anything for you, or does it feel redundant with what’s already out there?
For me site, over a newsletter (not that it wouldn't be bad to have a featured scape of the week/month that is presented almost as a newsletter). If it is curated, then I think there is potential to kind of sections things or build up on things. And it is not something that would be too much different from what this site offers, but something just a bit more organized from what I see here. I wish there was was a bit more of a gradient to how information in this area is disseminated. A lot of information feels like I'm going from the kiddy pool to the diving pool with no real in between (this could be on me). I also understand that doing this is more work. Having something where you can slowly start wading deeper into things I think would be nice.
Some of the journals will reach 200 replies in a little over a year and how people present the information is sometimes all over the place. By no means their fault, they don't know the future, they don't know when an algae outbreak is going to happen or a melt, and there is great discussion here around that. But it is hard as a newbie to sift through a lot of it. I know I can't prepare for everything myself, but with a lot of the scapes at some point having a more concise wrap up of everything. As of writing this, the most recently responded to journals have 54, 257, 18, 98, and 157 replies. A lot of media and content kind of stops at the setting up phase, then here for long running ones its a lot to sift through 257 replies.
• Would you ever visit or subscribe to something like that regularly, or is it a “look at once, forget” kind of thing?
Yes and maybe. Think while things are early and getting started yes I would. As for the frequency I would probably do it in spurts. Maybe is for the I don't know. If I truly love what becomes of this hobby that it becomes permanent for me then yes and no if it is something that dies away.
I am sorry for all of the rambling, this was partly something I wanted to get off my chest as a complaint for some things in the hobby

It could also be there is something that does a little bit of this, but I haven't found it quite yet.