Most webcams use USB UVC protocol which is supported on Linux. I have a Logitech Brio 4K webcam I use for doing YouTube videos (with OBS) and I have some cheaper Redragon webcam I use for video calls. Both work great. I also just picked up a 4K HDMI USB capture device that also uses UVC and it works just fine as well.

For graphics card, AMD is best. Intel is getting there as well. NVIDIA works but the drivers are proprietary, out of kernel, outside of Mesa, and painful to maintain. Do not recomment NVIDIA. I personally use an Intel Arc A770 in my main PC and it works fine for the games I play EXCEPT that Yuzu emulator runs like absolute crap with it, so this past week I swapped it out for my older AMD RX580 to play TOTK at 60fps.

AMD graphics cards work well in Linux. I used an RX 580 for quite a while and recently upgraded to a RX 6700 XT.

I don't have a webcam, but most of them work in Linux, just make sure it's UVC compliant.

No webcam. I have an AMD Radeon RX 6600 XT.

NVidia RTX 3070, closed source drives, rock solid. Open source drivers usually lag behind, and was pretty broken when I first got it.

Haven't seen a webcam not work in Linux in years, they are all mostly standardised. Have used Logitech, MS, and a HP camera, along with laptop built in cameras, all worked fine.

I use an RX6800XT for my GPU, and a Logitech C920 for my webcam.

AMD for graphics - RX 6600XT. Works flawlessly with the opensource drivers. I don't use a webcam currently, but in my experience most Logitech webcams work fine these days. Before you buy one, look it up on Amazon and search for "Linux" in the reviews and usually you should find a comment indicating whether or not it works fine.

Nvidia 1060 for graphics, got it back in 2017 and haven't seen the need to upgrade.

If I do change it, I'd be tempted to go AMD, but blender compatibility does have me worried.

webcam i sadly can't help you but on the gpu side i would try and search for a used one. i have an rtx 2080 super in my main system and an rtx 3050 ti in my laptop both seem to work fine under linux. i may have gotten lucky since i had no problems with the drivers. tldr in my experience 20 and 30 series rtx cards work.