Apple did a massive push to get the tv app and airplay into a variety of smart tv’s in order to launch TV+. So if you have a newer tv it may be supported.

Some "smart" tvs have AirPlay built in. (Samsung has some models). Ours did but we didn't know it initially.

There are also Lighting to HDMI adapters. I think it’s understandable they don’t support Chromecast for an Apple Watch centered service.

My hunch is that you are not Apple's target audience. They are fairly happy targeting specific users that are into their ecosystem.