Currently, ever single folder and sub-folder need to have the poll/push settings activated individually. Having a global "enable sync for all folders" or similar option, or alternatively having a switch with an "also sync sub-folders" option would be a huge QOL improvement. If performance degradation for older7slower devices is a concern, such options can come with the necessary warnings (or even confirmation dialogues) about performance and RAM usage.
When speaking about sub-folders, I am making the assumption that proper sub-folder handling (as partially shown in the V12 Beta version) will be implemented, of course. The current stable version of the app doesn't recognize sub-folders at all.