First time PC builder, help and advice would go a long way

Hi everyone !

I know I probably picked one of the worst time to build a pc but I've been wanting to do so for the past couple of years without taking the plunge.

So, as the title said, this will be the first time of my life that I build a PC. I just know the very basic things (and even that I'm not a 100% confident).
I would mainly use the PC for work (nothing fancy, just like using Office and things like that), and gaming, with one particular objective in mind. I'd like to be able to run heavily modded Skyrim and Fallout 4, Cyberpunk to a lesser extent. So, mostly single player game, with the occasional FromSoft game. Of course, I'd like to run more recent games and future release too.
A friend of mine built a PC not that long ago and I try to get inspiration from the parts he selected to make my own.
I currently live in China and have a budget of around 15k RMB (or 2.2k USD, 2k EUR). I could go a bit overbudget if really necessary, like 250 USD. I've made a build on pcartpicker, here's the link : https://pcpartpicker.com/list/dsd7R4

I do have a few questions regarding a couple of areas. I tried to do my own researches but I'm unsure if differences will be that notifiable or not and I'd rather ask different persons' opinion rather than AI.

- How does a 9800X3D compare to the R7 7800X3D that I selected ?
- Regarding RAM, I chose two different parts but I'm struggling to know the differences between the two, if any. Any alternative I should consider ?
- For the graphic card, considering the use I'll have for this pc, I'm still debating between a 5080 and a 9070XT. I know they are technically not the same class (the 9070XT being closer to 5070 in terms of performance from what I understand) but still.

I would love to have more enlightened opinions than mine on this build. Any recommendations or change you would make ?