Ryzen is a very good general-purpose CPU and if you're building a computer to do multiple things it's not a bad choice for its price. When it comes to purely single thread performance heavy workloads it tends to perform about as well as 3rd to 4th gen Intel CPUs in a clock for clock comparison. For situations that rely on heavy multi-threading then Ryzen can crush 3rd to 4th gen Intel CPUs.
The specific GPU that you pair with really any CPU, doesn't really matter as far as being able to play a game once it hits a certain level of performance. If you want to have really high resolution scaling or if you're someone that really wants to run enhancements like high-definition packs and other things then it matters more.
I will say for building a system for emulation though I would not recommend spending two times the price of your CPU for a GPU. If you're building a system to run native PC games then that's a lot more reasonable of a setup.
The specific GPU that you pair with really any CPU, doesn't really matter as far as being able to play a game once it hits a certain level of performance. If you want to have really high resolution scaling or if you're someone that really wants to run enhancements like high-definition packs and other things then it matters more.
I will say for building a system for emulation though I would not recommend spending two times the price of your CPU for a GPU. If you're building a system to run native PC games then that's a lot more reasonable of a setup.