FWIW, and this may be more appropriate on reddit than here, I’ve come across one deficiency of the Store version of desktop Office.
Using File Explorer, select a text file (.TXT extension). Usually it’s associated with Notepad. If you’ve installed a more powerful text editor, like Notepad++, .TXT files would be associated with that. However, if you wanted to open the .TXT file in Word, it’s not so easy.
Store desktop Word doesn’t appear in the default Open With submenu of the pop-up/right-click menu. Nor can a usable Word .EXE be found using Look for another app on this PC.