Yeah, I did fail to mention OPFS in the blog post. It does look very promising, but we're not in a position to build on emergent tech – we need a battle-tested stack. Boring over exciting.
The Rocicorp team have decided to focus on a different product, Zero, which is far less "offline-first" in that it does not sync all data, but rather syncs data based on queries. This works well for applications that have unbounded amounts of data (ie something like Instagram), but is _not_ what we want or need at Marco.