@randy both tunnel and cdn have free tier. “Argo” is strange product umbrella covering 2 lousy products. I just double checked and i have zero billed $ in my cf account for last month.
Scalability is good question. For real data it is better to ask author and operator. From architecture standpoint is good choice of bringing optional elasticsearch, stripping down unneeded features.
Sure you can scale out horizontally. You can bring more elixir web apps, postgresql replicas (for scaling reads), use elasticsearch(very scalable) for search and s3 compatible backend for media.
My concern is write scalability of postgresql. Hovewer, before your instance will grew out of capabilities of big postgresql server, you will have many other non-technical “scaling” issues and you may want to just create more instances and bubble them (which will ultimately solve write scalability issue. Another issue is federation peer-to-peer http connection pool / queue scalability.
My new video about setting up akkoma fediverse activitypub server has been published https://www.youtube.com/watch?v=GDCvCkSWKak
akkoma is hardfork of pleroma. After pleroma caught itself in web of politics, feature creep and bloat, alternatives emerged. Akkoma is one of them.
Some highlights, comparing to pleroma:
In a nutshell, what I do in video: