Pixel 8 is far above the 7 because it has Hardware Memory Tagging exclusive to it. GrapheneOS is the only OS using it in production right now, but it's an extremely large hardware-based security feature that provides memory safety for memory-unsafe code.

While it sounds boring to things the user sees like the Vanadium browser or what not, it's our biggest security feature of the OS. Almost all major vulnerabilities on the Android platform are to do with memory corruption.

Outside of GrapheneOS, the Pixel 8 also has 7 years of update support. If you aren't the type to buy a phone every couple of years then it's a good choice.

Get 8, always go for better hardware, plus is supported for longer.