I agree that Wuffs [1] would have been a very good alternative! ...if it can be made more general. AFAIK Wuffs is still very limited, in particular it never allows dynamic allocation. Many formats, including those supported by Wuffs the library, need dynamic allocation, so Wuffs code has to be glued with unverified non-Wuffs code [2]. This approach only works with simpler formats.
[1] https://github.com/google/wuffs/blob/main/doc/wuffs-the-lang...
[2] https://github.com/google/wuffs/blob/main/doc/note/memory-sa...