Diverging my eyes is very easy and painless. Crossing my eyes kinda hurts.
This is probably because I’m nearsighted and don’t use my glasses when using my phone and instead hold my phone 20cm from my face. They’re already crossed from doing that and crossing them even more is difficult.
Diverging your eyes is how magic eye posters work.
Here is a tool from Reddit user vibrunazu to convert between Cross View and Parallel View: https://vib-xibot.web.app/