I am very much a non-expert, but to my amazement, I have been able to get up and running with a smartphone running an open-source, non-evil OS, and can actually do almost everything I had used my iPhone for. It is possible! But the most important thing to know is that, unlike an OS for computers, an OS for a smartphone has to be surprisingly device-specific. I had to track down a 9-year-old Google Pixel 3a XL in order to run the OS I wanted. It's doable! If I could do it, you can do it!