I naively thought because I could install my own web browser on android that I got more privacy than having any web browser on ios having to use webkit undernea

I naively thought because I could install my own web browser on android that I got more privacy than having any web browser on ios having to use webkit underneath (where they could centrally "spy" or get info for ad targeting). For example if look for tor on ios, you find info reminding you of using the system webkit. Has anyone looked into whether (1) android does provide you more privacy by bringing your own browser or not, (2) whether apple in fact has no privacy when using a browser?