What's a SPF cream to protect against phone and computer's screen harmful rays?

Have you tried a tin foil hat? Some say it works against alien mind penetration too.

you don't wear it for that

None           

Just use the blue light filter.

5000000
Plus some Grade 14 welding goggles for your eyes.
Finding those should keep you away from conspiracy sites & hopefully you may start to regain your grip on reality!

Depends on the phone and it’s series number.  Since I have an IPhone 6, I use SPF 6. Buying SPF cream can get expensive so I usually wear a ski mask to save money.

Surprise, folks, SPF creams actually do protect skin against damage from blue light, which can age it. See below for some recommendations: