So I am looking to buy a new TV, but the latest smart-TVs all seem to be very bloated with ads and other ridiculous and unnecessary features. I know very little about TVs, and therefore wondering if anyone has any tips on some good TVs that include as little bloat as possible.
Not really. TVs are subsidized by ads and data collection, so they all have this crap. The more reputable brands do have better UX and may let you opt out of some of it, but not all.
My recommendation is to buy the TV with the best hardware features that you want. Once you get it, connect it once via Ethernet and update it to get all the most up to date features and fixes. Then disconnect it from Ethernet and connect a smart TV box like Apple TV or the nVidia Shield and use that.
Your experience will be better, the UI will be simpler, and you don't have to worry about all the ads and spyware.
Genuinely, what features and fixes could a TV possibly get from the internet besides applications that require an internet connection? If you're using an external device to watch your stuff, why would you need to update your TV?
Just speculating, but firmware updates might be useful. Some display resolutions, refresh rates, VRR, etc might not have been programmed correctly and later fixed. They could add new features like offsetting pixels slightly differently over time to reduce colour burn in or something that might reduce warranty claims (I don't really expect them to add more value to the TV through new features unless it would help them financially).
That said, I've never connected my current TV to the internet and it's been fine. I'd suggest trying an update if your TV does something annoying or isn't working as well as you'd like. You can also read about your model online to see if there are any updates available and what they do to determine if you want them.
For my Sony TV, updates have improved performance if I bothered to use the built in Android TV interface and it enabled 4K variable refresh rate support for things like the PS5.