New to Grav - Curious About External Image Storage and Responsive Image Variations

Hello All, I am new to the forum and thinking of using Grav. I'm coming from Craft CMS, and WordPress before that. Newbie question here: I am curious if anyone has had success in Grav hosting image files externally on a service such as an Amazon S3 bucket, and possibly even serving up various responsive image sizes via something like ImgIx? What options have folks used other than storing the image source files locally in a site folder? And what are folks doing for outputting responsive images in Grav? I appreciate any feedback! Cheers