The "Add Picture" control should have a property to change the target file type. Attachments have been lacking in PowerApps - the form based "attachments" are not very robust, however the add picture control has a lot more capabiliteis when you connect to blob storage or flow using the JSON function. It would be amazing to use this control for all attachments. The functionality is already present in the control.
When the file dialog opens after selecting the control, the default file type (bottom right of the dialog on windows) is "images" but if you select the dropdown and pick "all files" you can then see all files and choose and upload any file (PDF, XLSX, DOC, etc). This functionaly all works perfectly, but it is confusing & annoying to try train users to click "All Files" each time the dialog opens.
A simple change would be alow the add picture control to have a property where we could default the file selection box to "All Files" so the user can select anything. Would allow app makers to start fully implementing attachments into their apps.