Satechi
Satechi USB C Slim Dock for 24” iMac with Tool-Free Enclosure for M.2 PCIe NVMe and SATA SSDs– USB C Data Port, USB A, 2 USB 2.0, Micro/SD Card Reader (Silver)
mfep
mfep HD6970 Video Card for iMac A1312 2011 AMD Radeon HD6970M 1GB Graphics Video Card 109-C29657-10
SoNNeT
SoNNeT eGPU Breakaway Box 750ex - External GPU Chassis