Dedicated GPU?

Hello Comrades,

Thanks for all your advice about setting up Linux. It was a success. The problem is that I’m now I’m intrigued and I’d like to play around a bit more.

I’m thinking of building a cheap-ish computer but I have a few questions. I’ll split them into separate posts to make things easier. Note: I won’t be installing anything that I can’t get to work on Linux.

Do I need a dedicated graphics card? I'd like to run an HD display as a minimum. (I don't have a 4k monitor at but I wouldn't mind upgrading later if I can save up for one.) Mostly, I'll be streaming or playing videos.

I wouldn't mind playing some games but is a dedicated GPU needed?

If I should look into a GPU (I can always add it in later), what should I look for? (I'm not really interested in the latest AAA games). I wouldn't mind playing HOI4 or Victoria 3 as I hear so much about them.

What are your thoughts on second-hand GPUs? This will obviously cut costs but is there anything to watch out for?