https://github.com/AlekVolsk/shits/blob/master/layoutsmodule.php

https://github.com/AlekVolsk/shits/blob/master/layoutsplugin.php

There's already a module layout field - https://github.com/joomla/joomla-cms/blob/staging/libraries/legacy/form/field/modulelayout.php - what exactly are you aiming for with this suggested new field?

No, it is not, ModuleLayout selects the main module template, but there are modules with complex templates, when it is necessary to implement additional layers and, if necessary, to override them, to choose the necessary override in the module or plugin

For example, a module with a filter form, where each filter element is a separate layer, and layers of the same type sometimes need to be wrapped in a different way (for example, a list can be represented as a select, multi-select, regular list, group of checkboxes or radio, in any other way)

So you want to expand the suport of JLayouts to modules and plugins, similar to what we have already for components?

Yep ;)

JLayouts work everywhere as it is. The request is for adding a field type that looks up layouts in /layouts/ directory as opposed to /tmpl/ directory.

That sounds to me like a use case very specific to your extension which you can solve yourself with a custom formfield for that "creative" use of JLayouts.