I see, that is if you were to use iGPU, the one integrated in the CPU, basically how much regular RAM it can eat to use for VRAM, if you have no dedicated GPU. Which isn’t your case.

I’m not sure where you get that from, CPU doesn’t really care about GPU memory. Maybe you’re confusing it with newest AMD GPU lineup ? RX 7600 runs 8GB of VRAM, but there’s no correlation to the Ryzen 5 7600 CPU.

I think it’s doable, here’s quick example of what I could buy in Slovakia:

CPU: Ryzen 5 7600X - 250€

MoBo: ASUS TUF GAMING B650M-E WIFI - 175€

RAM: Kingston Fury 32GB (2x16) DDR5 6000MHz CL36 - 112€

Total: 537€

You could replace the CPU with R7 7700 but that’s maybe 100€ on top of that.

Regarding GPU, yes it still would be compatible and you could still replace that down the road with something more powerful, maybe when next generation of GPUs will arrive, I don’t know what resolution you’re running but 2070S is still relevant graphics card.

Considering CPU uplift, it seems to be more or less double the performance - link to benchmarks.

You can’t switch to AMD without getting a new motherboard (either AM4 or AM5 socket). If you choose to salvage as much HW as possible, then you can go for AM4 motherboard (B550 chipset for instance) along with some R7 5700X, then you can reuse pretty much everything else (probably cpu cooler too) else. Although I’d prefer to have at least 3200MHz ram sticks for Ryzen. I really don’t know if your video encoding is more stressful on your cpu or gpu, but generally AMD gpus work better for linux than nVidia ones do.