1) First, create all the (department) Teams sites from/in the Teams desktop Client - and in the underlying SP site and the General channel is created by design. 2) With SPMT -> migrate the various 'Folders and Files' to the Doc library.
However - Teams don't "recognize" that various folders are now in the Doc library, so no Channels are (auto) created in Teams
Afterward trying to create an HR folder - Teams reports that it can't create the channel ??
I was thinking; what about creating an additionel/seperate doc library for the migrated files - and create a tab in the departement Teams - that way the department/owners/members won’t experience any issues creating channels ?
Yes, you can so this many ways! Either you copy files to the channel folders, or you create separate libraries that you can pin as a tab in preferred channels or add as a cloud storage in the files tab!!