> I thought of AMD Ryzen 7 5700

Definetly not that one if you plan to pair with a dedicated GPU! The 5700X has twice the L3 cache. All Ryzen 5000 with a GPU have only 16MB, 5700 has the GPU deactivated.

I have a lower-end Radeon GPU (Navi 24 [Radeon RX 6400]). Which CPU would you suggest with it? I only ever want to use the GPU though, not the CPU's integrated one. I kind of want to get a motherboard that is compatible with the latest AM socket, which is AM5, right? So if I want a CPU with AM5, what would you suggest for the CPU?

But see, this is why it is so difficult. I would have never guessed. I would have to research this A LOT, which I am fine with, but you know.