The connective tissue between domains: ADCs and DACs bridge analog signals, CP2102 and CH9102F boards bridge USB to UART, and a whole sub-family exists just to fix I2C — extenders, isolators, muxes and address shifters.
ADS1115/MCP3421 ADCs, MCP4725 and GP8413 DACs, CP2102 USB-UART boards, and I2C plumbing like the LTC4316 address shifter — matched to bus, resolution and signal range.