Historically, the approach was to concatenate a string to itself with the new additions:
Set Variable $myList = "$myList, New Value"
I suspect it could be done with the new expressions feature that is in beta too which you could do some creative things with. Feel free to PM @support if you want to get added to the beta.
Edit: And thanks for sharing the video, @BeardedTechGuy ! I was thinking that Context Variables could have been a good way to streamline the garage rule, but we probably need to add a context variable to indicate a ‘state stays’ delay somehow. 