Beam Gen2

First we need to know what type of socket is available on the PC and the audio formats you want to use. Here is a discussion.

I’m not sure if you will like the overall results because you are likely to have lip sync issues.

My MSI Tomahawk WIFI AMD B650 So.AM5 DDR5 motherbord is equipped with a AMD Ryzen 7 7880X3D 8x 4.20GHz SoAM5 WOF prozessor. The motherbord does have a TOSLINK (optical) socket which fits with SONOS BeamGen2 supplied optical connector cable, having HDMI at the other cable end.

Since you mention S/PDIF, PC probably has a Toslink (optical) connection? If so Sonos sells an adapter from Toslink to HDMI, see https://www.sonos.com/en-us/shop/optical-audio-adapter. Using optical there should not be any lip sync problems.

Sonos themselves wrote this about adding a Sonos device as a computer speaker:

edit: just finalised this post after your last post. Toslink it is.

The SONOS adapter converts TOSLINK to HDMI-eARC -- which is the required input for BEAM (Gen 2).