Hi @FroggyFrog, welcome to the Sonos Community!
It’s possible that it can work but it’s not guaranteed as seen by the issues your running into: the Connect:Amp isn’t designed to be used as the main Home Theater component.
I’ve had a look online and most users mention connecting the Connect:Amp via a headphone-to-RCA converter if the TV has a headphone jack, though I’d assume a HDMI convertor should work as well. One problem that is repeated often is that there will be a 75ms delay on audio which you will notice.
My recommendation is to use one of our soundbars (besides the Sonos Ray) or the Sonos Amp, as those are designed to work with TVs and don’t need a convertor to work with HDMI. As you’re trying an unsupported setup, there isn’t anything I can offer in the form of troubleshooting other than making sure the connections are correct or trying a different converter.
The headphone-to-RCA converter is all I can see mentioned online, but other users may have other suggestions or steps to get the Connect:Amp working.
I hope this information helps!