my assumption for now
From The Lost Media Wiki
look, the only episodes that are in imagica probably wont get released, because the images from stuff imagica has jun also has and released. also, if this copyright and the series coming out thing is true, then imagica might be late to the party in the release if jun releases. besides a few episodes will be video only, thus making it harder to find more. i am also researching about zingo's "i hate report cards" rerun, ill keep updated on that
update: the doraemon wiki has a rerun airing list, which is super interesting because it doesnt say there were reruns in 1978 where zingo apparently got his rec. this could be wrong or whatever, but that could almost prove zingo's copy doesn't exist. sadge.