We have a customer (Unilever - global requirement) asking for Grammar spell check in our DXP platform. It seems that there are some options like Browser plugins (ej. Grammarly) or CKEditor plugins (https://webspellchecker.com/) or TinyMCE plugins (http://www.afterthedeadline.com/) but I wonder if adding some kind of OOTB integration in the product has been ever evaluated and if so, if it is something we are considering.
CKEditor / Tiny plugins will only work on WYSIWYG editors so for a full Grammar review of, for instace a content page (inline editing), content article based on structure, etc. more will be needed so only browser's plugins will work I guess