Google Sheets is a combo. The sheet display is canvas, but a lot of interaction is DOM (and—notably—all text is initially stored in DOM, but then paged out for perf reasons as the above commenter mentions).
That said, X-Spreadsheet does also use DOM for some text interactions at least—seemingly much less so than Google from what I can initially/briefly see though.
That said, X-Spreadsheet does also use DOM for some text interactions at least—seemingly much less so than Google from what I can initially/briefly see though.