In Premiere Pro 25.6 Beta, my UXP plug-in does not load.

[updated status]

Hi broadcastingengineer, 

I'll start at the end; CEP extensions are 100% definitely still supported. The plan is to continue to support them for a calendar year beyond the release of UXP extensibility (in non-beta PPro builds). 

As for getting UXP plugins to load without involving UXP Developer Tools (UDT)...

Your built plugin directory should be placed within:

~/Library/Application Support/Adobe/UXP/Plugins/External

But wait! There are further requirements. 🙂

The name of your plugin's containing folder must consist of:

1. The id declared in the plugin's manifest.json,
2. followed by an underscore _ , then
3. The three digit version number, also from the plugin's manifest.json.

For the unmodified 3psample example, that means that the plugin's directory shall be named:

com.adobe.ppro.samples_1.0.0

 
Following [above], I'm able to load the 3psample in today's PPro beta build, without UDT.