My idea is:
In themes you can install a theme from a zip and you can delete an installed theme.
However if you are developing themes it can be cumbersome to change the code, zip the files, delete the theme and then install a new version of theme code from a zip each time round the loop.
Now I was mistakenly just replacing a html.twig file in a custom theme and found out Mautic does not always reload the files. There must be some caching going on and clearing the cache using the console command does not improve the situation.
Therefore, in addition to theme install and theme delete what about adding a theme refresh menu feature were Mautic reloads one or many theme from files. This would speed up the whole theme development cycle. The code must exist as part of the theme install feature. It just needs a new menu item to do the file reload or refresh.
Thanks.