I feel like chrome apps were actually ahead of their time and very much better than embedding a full browser per app with electron. Of course, they were not perfect but IHMO made much more sense than what we have today, at least on a technical standpoint and could have evolved into something truly great.
I.i.r.c. Chrome Apps are compiled binaries specific for Chrome (NaCL), they're more like Flash, Java or Webassembly applications.
NaCl was supported in Chrome Apps, but most Chrome Apps are just web apps using the chrome.* APIs, not NaCl.