Fil-C has like one "linear memory" per object and each capability gives read/write access to the whole object.

But Fil-C has its compiler which does analysis passes for eliding bounds-checks where they are not needed, and I think it could theoretically do a better job at that than a WASM compiler with multi-memories, because C source code could contain more information. Unlike WASM, but like CHERI, every pointer in memory is also tagged, and would lose its pointer status if overwritten by an integer, so it is still more memory-safe in that way.

It has a separate address space for each object? That seems unlikely. Is it not pretty much a software implementation of CHERI?