Not at the moment, but it’s a neat idea.
@James has been working on some proof of concepts around using variables in Rule Engine Notifications which requires a similar ability to inject a variable into a string though…
And we have an Rule Engine: HTTP Webhook Trigger feature request topic created, so I’ve gone ahead and created the other side of that which would be a Rule Engine: HTTP Request which you may want to vote on.
My thought is that you could create a rule (or rules) to make the HTTP requests and if those had the ability to mix variables in with other text, it could achieve what you’re looking for.