Live connection to data sources you connected your diagram to in Visio is not supported out of the box. (Visio Online does support this, for sharepoint lists at least)
Out of the box, if data is coming from a SharePoint list, you will need to re-publish.
It is possible to have dynamic values, but you have to do it yourself.
For example, to have these values dynamically you can do it with javascript:
Like, in the template you can put something like a placeholder to receive the value (I've set id to "placeholder1")
... something ...
<div id="placeholder1" />
...
And add use some javascript code (in the "script" tab), like this (if the data comes from some API):
fetch('http://some.site.com/movies.json')
.then(response => response.json())
.then(data => document.getElementById("placeholder1").innerText = data);
Here is an example of such approach (temperature data used for coloring and tooltip data is coming from a free online weather service):
https://nbelyh.github.io/svgpublishdemo/demo/EuropeWeather2.htmlYou can also use the same technique to get values from SharePoint lists (using REST API), but you'll need to write some code like this.
You can use SharePoint ID for example to get the item (it is available from extension). I think I will make an example of such a setup, but not sure when.
Note that you can also run the code in response to the user clicking some shape or some control (like, you can add a button or edit box to the template), or on selection/view change.
The code has full access to shapes; the extension provides shape data to javascript code using API.
Information such as shape text, shape properties, connected shapes, layers, etc is available to the javasript code.
There is autocomplete (start typing diagram. )