Moving and merging all digiKam items

I have a large collection (over 206K items) scattered around in many temporary directories on an external (USB-connected) HDD, that I added by Settings -> Configure digiKam -> Collections -> Root Album Folders -> Collections on Removable Media.
My current database type is SQLite (QSQLite) which is a bit slow sometimes. My setup is digiKam 7.7.0 on Windows 10.

How can I move all the items to new directories without using digiKam for this action and also without losing any digiKam info such as tags and labels?
By moving the images around, some of them may have to get renamed. Would this cause any problem? How to avoid it?

Outside digiKam, I use TeraCopy to get the files verified after copying. Does digiKam have a fail-safe file verification for moving images or albums?

Any input would be much appreciated.

I would make certain digiKam had been set to write this information into the files and not just remembering it in the database.

Under “Item”, there is a command “Write Metadata to File” ; my understanding is this will write digiKam information into selected files where the option to always do so has not been in play.

I hope this is helpful.