I am currently working on a 3rd party style system, that basically works on the new gutenberg style engine.
A cornerstone of this system is that I need to filter the block attributes for the HTML comment attribute rendering process. I have searched in the /packages/blocks/src/api/serializer.js for an applyFilters hook that I can use, but to no avail.
The basis for my style management is a datastore called "my/store". It provides additional operations for handling style attributes and a backup system, which you will read about below. Its stored objects are clientId-based, so don't wonder why there are clientIds in the store method.
I first filter the save block process as usually.