I am in the same boat so to speak. Buy I am learning towards keeping the P4XL. It is just too smooth. Camera can't be touched IMHO. It takes motion shots without all the blur my S20+ has. Then the one thing we all do with our phones more than anything is unlock them. FaceUnlock is better than anything Samsung has right now. Heck it is better than FaceID IMHO.
I get it. Its definitely close. A lot closer than it should be when you look at the devices on paper but the software on the Pixel is just top notch.
That said, OneUI is really good. I get the criticism that its too complex and has too many features. But it really lets you tailor things to your needs. Plus, theres literally nothing left out.
It would be easier to get rid of the S20 if the screen wasnt so perfect. The display on the Pixel isnt bad by any means, but it doesnt touch the S20 display. Its brighter, better colors, and even the coating on the screen just feels better.
I am actually getting good shots with the S20 camera. It really only struggles with low light and a little shutter lag. I find that even though theres shutter lag, if the lighting is good I dont get blur. It doesnt touch the Pixel camera, but its better than any previous Samsung Ive used. And video quality blows the Pixel away.
When it comes to unlock, Pixel easily wins. Face unlock is great. Its the best biometric Ive used to date. I havent been bothered by the fingerprint sensor too much becasue at home I used smartlock so its just a swipe to unlock. But thats still one step more than the Pixel needs.