Tilvids is a curate list of edutainment. So you can reach out to them and they can get you added. share.tube seems to be general purpose. diode.zone is an open general purpose. peertube.tv is run by Stux that's been very active in supporting Fediverse platforms and you can ask them to join on their mastodon https://mstdn.social/@stux .
If none of those fit the bill you can always check the general instance list: