@rmartha - there is not currently a way that I know of to use the result in the next option lists url as a variable like you are looking for.
Here is an idea already posted for this support that you an vote on. Passing value to REST type option list
You could however use that app id from the first option list in your script to call the state file endpoint, pull the needed info from the sate file and then use that info with your boto 3 tasks. It just wouldn’t be presented to the end user as a select list.