SMSL PO100 2024 192kHz USB to Optical Audio Adapter, XMOS XU316 Type-C USB to SPDIF Optical Coaxial, Portable Digital to Analog Converter for Phone/PC, Silver

There are cheaper generic things that will probably work but stay away from weird random no name stuff. The SMSL PO100 is the cheapest option I know of that uses a proper good known USB to SPDIF bridge chipset (XMOS in this case) so thats what I'd suggest.