I haven't looked at fs-verity at all, but per-file merkle trees should definitely be built into the filesystem as a standard thing. Rsync and file transfer programs want it, and having to compute that every time is crap - if it's built into the filesystem it can easily be computed lazily and invalidated if need be.

(obligatory plug for people to jump in and get involved with writing code if they want to see more of this stuff happen)