I’ve already saw the video you are showing but i dont really see how we could workaround this to apply this to our problem… 
We do have a dedicated hosting with cpanel on wich we can create postgreSQL database, do you think there is some kind of workaround to copy all our local content ( collections, components and uploads ( images ) ) into a postgreSQL database on our server THEN share it also with our heroku app ? So our heroku app access this data ?
This is the only workaround we thought about… The thing is we alread imported manually something like 1300 images and created a ton of stuff so we really need to figure out how to migrate it, we cant offer to take 3/4 days to import it again from scratch…