Can I use a variable as part of a string in rule machine?

I have a new date time variable. Can adjust it as desired with RM. Then want to use the updated variable as PART of a string input for a custom command, e.g. VoiceCmdAsText which sends the string to Alexa. For example, I have a variable %Wake time% and want the custom command to send the string "Wake me up at %Wake time%"

Possible?

What you want works for me in Rule 5.0 (never tried in Rule 4.x, so can't speak to that, but it sounds like you're using 5.0 given your DateTime variable):

Unlike when the variable is the entire parameter string, Rule Machine doesn't display the "real" value in the UI for the parameter, but it does work. Here's my device after the actions ran:

Screenshot: device showing attribute set to above string

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