Initial impressions: Looks like a relatively new project -- only 59 commits, all by one person, starting from last September. And based on a GitHub search for "ficusjs," it seems that no other projects mention it. It's only a bit over a thousand lines of code, and based on a cursory glance, the code is in pretty good shape. It should be able to fit entirely in your head, and for a lightweight framework, that's a good…
The first-blush API for defining a web component looks pretty nice and simple. Probably won't have the best performance in the world but that's fine for situations where I just want to sprinkle some interactivity to a server rendered or static site.
The store looks nice in some ways, but the actions/mutations language looks very boilerplatey and convoluted. I feel like I'd want something much simpler like jotai or zustand.
The event bus... seems on first blush like it'd be awkward to mix multiple event buses into a single component?