I've never owned a TV before but recently purchased a Samsung TV.
In terms of privacy, is it recommended I use its internal OS to log into things like Netflix or Disney+, or is it better to use a Chromecast for those things?
I figured if I use a Chromecast I can simply not connect my TV to the Internet at all. Of course, it does mean I'll be using a Google product.
And what privacy related issues am I opening myself up to in the first place? What kinds of things do TVs and Chromecasts track?
In any scenario the brand of smart TV is irrelevant as thet all impair your privacy. Cost and effort are sadly now a feature, but not too much of a challenge. Never connect your TV to the internet directly. The easiest step is a Chromecast. I recently needed to replace my dumb TV with a smart TV. For me I just bought a TV at a price point that allowed me to also buy a used old PC box plus a wireless keyboard a touchpad. You could alternately use a Raspberry Pi. Either way, you ultimately have control of what is shared or escapes for your privacy.