My connected devices have a USB-A connection, so I could use a USB-C to USB-A adapter.

Good evening, I don't know exactly what you mean by the question... But I can tell you that many older devices need a USB 2 or 3, the USB-C in the iMac can be used with an adapter from USB 2/3.0 to USB-C, USB hubs usually don't work because the power is only sufficient for one connection, possibility see digitec.ch article number
14052440