Current situation:
1. SharePoint list with data entered daily by user(s).
2. Power BI report (data source: #1 above) that displays summary snapshot-in-time. (auto-refreshed daily)
3. Power BI dashboard (data source: #1) with three tiles that each display snapshot-in-time value. Data alert set up on each tile. (auto-refreshed daily)
4. Three similar MS Flows: each is triggered by the above data alert on the corresponding tile, and each adds a line to one of three tables in one Excel sheet (resides in SharePoint doc library). (auto-executed daily)
5. Power BI report (data source: Excel sheet, resides in network folder \\server\folder) that charts data from the three tables. (auto-refreshed daily, gateway set up and functioning properly)
6. Once-daily, file from #4 is manually copied to #5.
Issues/Problems/Questions
1. The need is to trend the data for three data points in the SharePoint list in #1. Thus far, only way discovered to do that is to take a snapshot daily of the values (#3 and #4 above).
2. It has to be able to auto-refresh with no user interaction and no need to have my (SharePoint library owner) laptop on at the time of refresh.
3. No known way to have Flow add a line directly to the Excel sheet in #5 above.
4. No known way to have Power BI source data directly from Excel sheet in SharePoint doc library (#4 above).
5. No known way to have Flow automatically copy the Excel file from SharePoint doc library to network folder.
6. No known way to include SharePoint doc library item in data gateway.
Hope I've adequately (and clearly) conveyed the situation and our needs. Hoping that someone in the community either has direct solution(s) to Issue/Problem/Question #3, 4, 5, or 6, or can come up with "outside-the-box" ideas that would achieve the desired result.