Migration from intel mac to silicon

My old Imac died so I cannot access the drive, won't power up. I removed the drive and connected to an external enclosure and connected to new mac M2 pro. Old drive is 2TB new internal is 512G. I think the new mac recieved files and data from the cloud (I didn't know what the setting should be). I also have a 4TB M.2 stick in the same enclosure as the 2TB ssd. I want all my data on he 4TB stick and only want system and other necessary files on the internal drive. Once that is done I will use the 2TB ssd as time machine. I assume I don't want to migrate the old intel sys to the new mini m2. What is the best way to proceed and clean up the apparent mess that is already on the new mac. my new mac is mac mini (2023) M2. It does not show up in the list of devices I can select.