Noob Question: If you aren't willing to deal with custom OSes like Linux (for computers) and Android Custom Roms (for phones), do you just not have any privacy at all?
I mean, exactly how invasive are default operating systems? (Like Windows, Mac, Chrome OS, Android, iOS) Do they log your keystrokes, log passwords, capture screen, upload your photos, videos, or audio? (Assuming you aren't a target of government) Is it even possible for the average person who doesn't feel comfortable messing with installing operating systems to have any privacy?
Privacy is not binary. There are degrees of privacy that can be achieved. Where you would like to be is totally based on your personal situation. If you are a beginner, understand that privacy is a journey.
Regarding which OSes you could use for your computer if Linux is not an option:
Windows in my experience is the worst offender when it comes to telemetry. It is so ingrained in the OS that you'll never be certain there isn't any telemetry regardless of the measures you take. MacOS on the other hand can be configured in such of way that Apple will have very little if any telemetry on you. It also has good permission controls which would cover things like screen capture and logging of keystrokes which you mentioned above. You could do the following:
Purchase a Macbook
Opt out of using an Apple Account (as of today it's optional)
Opt out of using iCloud
Opt out of any telemetry
Turn on built-in firewall
Turn on disk encryption
Install Lulu or Little Snitch to block any Apple telemetry
This alone will probably put you in a better position than 99% of people (not an actual statistic).
It might be degraded comparing to default experience but it’s not like you are missing something that you have on other OS. I mean, you can’t iMessage on Linux, right?
Agreed. I was using Apple products for more than a decade before switching to Linux and Android, and I opted out of several of their products long before I started considering the privacy aspects of things. For example, I found the experience of using something like iPhoto to be very lackluster. I reluctantly ended up using iCloud due to the superior pricing compared to Dropbox, which I used before. That was a particular nightmare when migrating away from the Apple "ecosystem".
I'm sure their products cater to many users preferences, but I'm not one of those, and had a better experience using other products. That should've made me jump ship way earlier than I did, but a combination of cost (by the time I would've changed, I had already purchased a new MacBook which I ended up using for about 6 years) and inertia.
I use my Macbook exactly like the points cited before, and i can assure that i've had a very good experience.
Maybe it's even better to avoid using AppStore etc...