External Hard drive for MacBook Pro M1

Hello drei_30,

Thank you for using Apple Support Communities!

We understand from your post that you would like to know how many external hard drives you can connect to your MacBook Pro M1. This article has information about connecting multiple devices to your Mac which you may find helpful:

About USB on Mac - Apple Support

"About connecting multiple devices

You can connect more than one device to a USB port  by using a USB hub. Connect the devices to the USB ports on the hub, then connect the hub to the computer. Most USB hubs have a power adapter and should be plugged into an outlet.

Be sure to connect USB 3.0 SuperSpeed devices to a USB 3.0 SuperSpeed HUB, USB 2.0 Hi-Speed devices to a USB 2.0 Hi-Speed hub, and so on."

Best Regards.

You can connect as many external drives as you like, limited only by having places to plug them in. As suggested, Hubs can extend the number of places to plug in far beyond what is reasonable.