The display of the favorite folders up to Thunderbird 102 was reduced and the arrangement in groups ensured clarity. This plugin brings this type of representation back to Supernova (115+). The plugin meets very specific requirements and in the current version does not have any configuration options. If there is appropriate demand and feedback, the range of functions can be expanded. The source code is documented in detail on GitHub
and can be used as a basis for your own adaptations.