Have you looked into script-fu? It would probably be a very steep learning curve.. BUT there is an opportunity to do something impossible 10 years ago, and that is to use AI and an external application. BATCH-FU is one such attempt but it seems to be a 'select action from a menu' thing.
But Gimp developers: implementing batch in one go is a big ask I know. But a great first step might be to create a channel in Gimp where correct script-fu is emitted for operations in progress. Being able to connect to that from outside would allow 3rd party projects to assemble "record by doing" macros that could be turned into Photoshop-like batch capability.
Macros are on the roadmap (https://developer.gimp.org/core/roadmap/#macros-script-recor...), and in fact we did a lot of prepwork for them during 3.0's development (internally, several features like filters and plug-ins now have configs that store settings, which will be used by macros in the future to repeat operations).
But Gimp developers: implementing batch in one go is a big ask I know. But a great first step might be to create a channel in Gimp where correct script-fu is emitted for operations in progress. Being able to connect to that from outside would allow 3rd party projects to assemble "record by doing" macros that could be turned into Photoshop-like batch capability.