It's pretty much impossible for us to know just how accurate a picture of us can be harvested, aggregated and inferred, because there's no transparency. And while I like to feel like I'm pretty safe because YouTube and others don't do a particularly good job of recommending content to me, who knows whether this reflects what they are truly capable of - maybe their recommendations are deliberately dumbed-down for this very reason.
I use Protonmail for the bulk of my email, DuckDuckGo as my search engine, AdGuardHome for DNS and Firefox for browsing. Curiously enough when fussing with DNS, I discovered that it wasn't enough to alter my router's settings to point to my chosen DNS, I had to disable the service entirely on the router, because while I could redirect IPv4 DNS, I had no control over IPv6 DNS, and hence, some ads and trackers were bypassing my ad blocker.
Trust-wise, I like Nintendo, am fairly okay with Apple (mostly because they are one company which is so staggeringly wealthy that I believe them when they say that the data remains within Apple, save for whatever leaks out to app developers or through contractors).
Smart TV and smart-ified UHD disk player are occasionally hooked up to ethernet in order for me to check for firmware updates, but otherwise remain offline with no access to wireless. I do lose some "free" Samsung streaming content, but that seems to amount to reality TV programming, so no great loss there. Bulk of video streaming passes through one device: Apple TV.
Revo Superconnect internet radio talks to a database operated by Frontier Semiconductor. No user account needed. Even better is Moode software running on Raspberry Pi, which taps into individual stream providers directly, at the expense of rather fussy setup and the need to ferret out the actual stream URLs.
Marantz AVR has diagnostics reporting switched off. Making the most of HEOS Music requires an account,, but basic functionality works okay without one.
Facebook, Twitter, Nest, Instagram, Sonos, Google, Spotify, Pandora, Microsoft Hello, Roon and cloud-connect IoT in general: Nope.