First off, please go to this community link and upvote this as a new feature: https://community.alteryx.com/t5/Alteryx-Designer-Ideas/Data-input-from-open-file/idi-p/921332
As a workaround, I drafted a potential macro that can be used in the interim.
What is is for? This macro serves 2 purposes:
1. Allows Alteryx to read Excel files as input even when that file is already open (This works for execution, but not the initial configuration)
2. Improved speed for shared drive connections (Input tool is very slow for network drives - 10 mins on network vs 20 secs on local drive)
How does it work?
It uses the run command tool to copy the original file into a temp file path that is on the local machine. This allows Alteryx to then dynamically read from this copied file instead.
