Well... the cheapest VPS vendor I know offers something as low spec as 256MB RAM + 10G Disk(1). You might meet OOM Killer for just running Docker install script, don't even think about putting a Minecraft server on.
It really comes down to what you want to achieve. Based on my experience, they're good enough as proxies, but I wouldn't install a database on there.
Keep in mind, you get what you paid for. Many low cost VPS vendors are also using low cost IDCs to host their hardware. Some of those IDCs might be heavily sanctioned by other online services (say, Google will always want to verify if you're a human if the IP of the VPS lands on the sanctioned range).
Other than that, they're fine. My VPS with Virmach has been up since 464 days ago, I consider it stable enough (again) for my application.
If you're interested in low spec VPS, I would point you to Low End Talk (https://lowendtalk.com/), which is a forum for low cost VPS vendor and consumers.
1: https://virmach.com/cheap-kvm-linux-vps-windows-vps/
I only need it's IP address and network, nothing else, to setup a stateless reverse proxy. Which I guess is the best use case for such VPS.