User defined mask as input, or erase/restore feature

[SolessChong]

Really nice project!. I'm looking at integrating with my site. However my users are looking for interactive process, or pre-defined mask prior for the background removal task, as the Erase/Restore feature implemented on remove.bg. Is there any way to do that? My thoughts are feeding the mask user drawn in some step  of the iteration, or feed the map into some layer of the unet. Could you provide some help or direct the right direction?