You might be surprised. The U2IrDA Mini 4 MBPS FIR USB IrDA 20 is far from obsolete. Its primary users fall into four categories:
macOS dropped IrDA support after OS X 10.6 Snow Leopard. For modern versions (10.12+), you must run a Linux virtual machine (VMware or VirtualBox) with USB passthrough or resort to a serial terminal connecting to legacy hardware via a different protocol. U2IrDA Mini 4 MBPS FIR USB IrDA 20
Some manufacturers provide signed drivers for their specific U2IrDA clones. Look for "Win10 IrDA driver" from FTDI or EXAR. However, be aware: You might be surprised