Hah, thanks. I meant, are there any open-source hardware/software solutions for feeding in a coax input into such a setup to get the full modem/router experience
Oh, for cable modems? No, there's no cable-modem-on-a-card. You should be able to get straight DOCSIS-to-ethernet bridges, assuming your cable ISP will permit them on-net. Arris CM9200, e.g., is DOCSIS3.1 to 2.5G ethernet.