Yes from a design philosophy standpoint vis is closer to kakoune than {neo,}vim. The implementation is quite different though (no C++, no boost, no home grown scripting/extension/syntax highlighting language).
Regarding vis, Lua is optional (you lose syntax highlighting though). libtermkey is a 3 file library and despite what the author claims it works, is useful and could be maintained in the vis repository if necessary.
If you think anything C++ related is lighter than something C based, then we just have to agree to disagree.