When creating PowerApps mobile form for SharePoint custom list with attachments, you can add the attahcment field as a card. To add attachments, you get three options - Take Photo, Select Photo, Browse. My idea is to control or restrict these options. In many scenarios, management wants to restrict the option to "Take Photo" only, so that the users cannot upload files already existing on their mobile device. For example, in retail store opening process, the user must capture photo to show merchandise display setup. In this case, the user must not be able to upload yesterday's photo.