That’s how my current computer still works. But to achieve that, I do not use:
- any Apple software
- Windows, or any other Microsoft software
- any Google service, not even their search engine (and especially not any Web browser based on Google Chrome)
- Web services from any giant enterprise known to thrive on personal data
- a Web browser without content blocking (ads, tracking, actually anything that I did not explicitly allowed in the first place)
- any proprietary software, outside of single-player video games

For someone who is already stuck with one or more of these things, migrating away might not be an easy task. Here I got lucky by avoiding most of these since my first days using a computer, and dropping the last ones quite early.