To simplify things and help our users to be more productive, we have archived the current forum and focus our efforts on helping developers on Stack Overflow. You can post new questions on Stack Overflow or join our Discord channel.
If you define your own renderer then naturally you'll have access to the cell render-time. Afterwards it may be harder since <vaadin-grid> 1 hides all rendered cell content inside the shadow root. Perhaps firing an event from the cell content element and catching that at Grid level would work for you?