Joomla 4 template namespace

Question

I'm working with latest Joomla 4 beta, and wondering how can I use namespaces with templates so I can start using and developing custom fields for my templates.

I need to know what should I set in the templateDetails.xml file so I can use proper addfieldprefix address for my custom fields.

Some context:

• what I have and currently use is based on my previous questions asked here: plugin defined custom field - partially works with addfieldpath for templates, use plugin defined custom field inside another plugin, setting extension namespace
• no matter how/what, using addfieldprefix inside the templateDetails.xml and linking from a plugin doesn't work; EG addfieldprefix="Joomla\CMS\Plugin\EditorsXtd\Vimeo\Field"
• I also found no documentation, stackoverflow or any resource about using namespaced custom form fields inside templateDetails.xml, I only found the libraries/namespacemap.php and seems only 4 types of items can use this system: if (!in_array($type, ['component', 'module', 'plugin', 'library'], true))

Open to any suggestion.

Thanks