A DNS verification page is only useful to someone who thinks to open it. The people who most need to see a failing DKIM record are exactly the people not looking for one.
The workspace dashboard now carries an infrastructure health card: the state of your domains and mailboxes, summarised, with anything failing called out. It is on the screen you open every morning.
Green means launch. Anything else is a link straight to the specific domain or mailbox with the problem.