Fairly little. Decentralization should take into account how redundant our nodes are, as opposed to how many nodes are there. I suppose it wouldn't matter that much if there are tons of nodes in certain areas or datacenter.
You are true! It's meaningless to run many bitcoin node on Contabo, it won't make things more decentralized. And to be honest, it's better to buy a cheap laptop or Raspberry Pi. Everything can be done under $100.
Those are some really cheap VPS, is the first time i read about Contabo, they have nice reviews in trust pilot, and I'm tempted now to get one VPS with them.
I hope you haven't bought their VPS, have you? There is a reason why they are so cheap. If you have a look at their plans, yeah, sounds like one of the best bang for your bucks but when you buy it, you understand that performance is nowhere what you were expecting from the given plan. If you simply need RAM, then probably buy them. By the way, I think no one comes close the performance and prices when there is a Hetzner. But you can't run Bitcoin node on Hetzner. But why should you run it on a VPS when you can just buy a cheap Laptop? This way is also better for decentralization.