I did not follow the requirements in detail, but e.g. the legacy but quite good ESI Juli@ has an SPDIF receiver chip with 8 inputs, of which currently two are used for TOSLINK and coax. Switching is controlled from the alsa driver which could easily be extended for more inputs. Yes Juli@ is PCI, but inexpensive PCI-e - PCI adapters exist, no 12V/-12V voltages are required for the digital board of the soundcard, refurbished amd64 thin PC clients have PCI-e ports and cost less than bare RPi4 (including top-quality power adapters), etc.