A computer-implemented method, comprising: accessing, at a user device, digital content data that includes a plurality of content items generated by applications (122, 124, 126, 128) executing at an application level on the user device for presentation by an input/output system of the user device, wherein the accessing comprises capturing, from the applications, the digital content data including the content items that have been processed by the applications for presentation by the applications; prior to the captured digital content data being presented to the user by the input/output system: for each content item of the captured digital content data, determining, at the user device and by a filtering machine learning, ML, model of a system level filtering operation performed at the operating system level and separate from the application level at which the applications are executing, whether the content item is to be presented to the user by the input/output system or filtered by the filtering ML model; for each content item of the captured digital content data that is determined to be presented by the input/output system to the user, allowing the input/output system to present the content item; and for each content item of the captured digital content data that is determined to be filtered, precluding, by the filtering ML model at the user device and by the system level filtering operation performed at the operating system level and separate from an application level at which applications are executing, presentation of the content item to the user by the input/output system. accessing, at a user device, digital content data that includes a plurality of content items generated by applications (122, 124, 126, 128) executing at an application level on the user device for presentation by an input/output system of the user device, wherein the accessing comprises capturing, from the applications, the digital content data including the content items that have been processed by the applications for presentation by the applications; prior to the captured digital content data being presented to the user by the input/output system: for each content item of the captured digital content data, determining, at the user device and by a filtering machine learning, ML, model of a system level filtering operation performed at the operating system level and separate from the application level at which the applications are executing, whether the content item is to be presented to the user by the input/output system or filtered by the filtering ML model; for each content item of the captured digital content data that is determined to be presented by the input/output system to the user, allowing the input/output system to present the content item; and for each content item of the captured digital content data that is determined to be filtered, precluding, by the filtering ML model at the user device and by the system level filtering operation performed at the operating system level and separate from an application level at which applications are executing, presentation of the content item to the user by the input/output system. for each content item of the captured digital content data, determining, at the user device and by a filtering machine learning, ML, model of a system level filtering operation performed at the operating system level and separate from the application level at which the applications are executing, whether the content item is to be presented to the user by the input/output system or filtered by the filtering ML model; for each content item of the captured digital content data that is determined to be presented by the input/output system to the user, allowing the input/output system to present the content item; and for each content item of the captured digital content data that is determined to be filtered, precluding, by the filtering ML model at the user device and by the system level filtering operation performed at the operating system level and separate from an application level at which applications are executing, presentation of the content item to the user by the input/output system.