So there’s a lot to reply to here…
Well… I got in to it and learned a lot about it. I’m not an expert anymore as I’ve forgotten more than I probably remember.

So with this, I’m pretty familiar with SquashFS/LZMA and live overlays from the Gnu/Linux Live CD/USB world and installer package archives from Mac OS – I think I can picture CFS if it’s like those.
From what I recall, it was a lot like BFS, but with compression, and the file attributes in tracker were broken on the builds I used.
If you used CFS it probably halved the install size of your build. That much I remember. Then Crushing saved a load of space.

Was reading more about OpenBinder here… interesting!
https://www.osnews.com/story/13674/introduction-to-openbinder-and-interview-with-dianne-hackborn/
Binder was def in the later builds. Certainly BeIA 2.x had it. I think it was in the earlier too… like you can embed exes in web pages and stuff like that and I tink that was achieven using some of the Binder functionality.

I kind of got that impression (that the start page was the interface) from looking at the eVilla UI… I didn’t know what powered it though! Nice – but why they’d go with Opera (a closed source browser)?
Expediency. Opera developed the browser for them. The Mozilla port was terrible at that point. This was back when the BeAPI made porting legacy code a terrible chore.

So from my research for the BeIA part of the Hardware page on Land of the Leaves I found out there were several devices besides the famous eVilla – but I always thought that the eVilla shell was the UI for BeIA so I got to learn something new
There were loads of devices. Some of which you will have heard of but assumed another OS was the only that ever graced the hardware. The Clipper, the IA, The Audry, the DT range of webpads (Dt300, DT325 for sure), and a fridge - there was a fridge concept.
The eVilla was terrible hardware because the tube was on its side and all the text and graphics needed to be rendered in rotated form … I kid you not.