Alan can show you his example of triggering a Rule Machine routine using its "Cloud Endpoint" URL, but here's a very similar way of sending a command directly to one of your Maker API-subscribed devices using a properly configured Cloud URL embedded in an email:
With a little extra work, you can get the outbound notification** from your hub to contain a neat hyperlink like I'm showing... but if you're content with just displaying the naked URL in the body of the email, it would look something like this:
Either way, the recipient could click (or paste) the URL to make it "go" and thus command the target device (this one turns on my desk lamp).
**Composing & sending these notifications from your hub is left as an exercise for the reader, but obvious choices would include Pushover Notifications Driver or Sendmail Notification Device. I hear others have also used Twilio Notifications Driver or Textbelt SMS Notification Driver or HEmail Simple Email and even IFTTT (still supported?) to generate SMS and email messages, something Hubitat no longer offers natively. (I haven't tried formatting such a link for sending as a Notification to my Hubitat mobile app, though if I'm sitting there with the app open, I'd probably just execute the command manually using that.)