Hey @Joaquim_Braga and @Heath ,
In our applications we also had the need to share information between dashboard blocks. And there is a possibility to exchange information between custom HTML Blocks (Iframes), using the same system that is used to receive queries updates on the dashboards. In this case, we use PostMessage (Window.postMessage() - Web APIs | MDN) available in browsers, but it is necessary that the dashboard is inserted in an experience page, and in that page exists a script responsible for receiving messages and sending them to blocks (Cross-window communication).
But an interesting possibility would be to be able to configure a general block, which would load information/characteristics in the other blocks, because in some cases we have style changes, or common scripts used in the blocks, which we made the external storage and imported in the blocks, but if the path of these files is changed, or we upload a version of the file, it must change in all blocks, if there was the possibility of loading in one place, it would be an interesting feature.