The MiniPCs really improved a lot last couple of years, they are good enough to use as spare PC.
Unless you game or work with graphics, they could replace a large PC entirely, specially the newer models.
Could also use a laptop or tablet when the PC does not work, but a MiniPC like this one is cheaper.
And it can be hooked up to your regular PC monitor, mouse and keyboard.
Must look around a bit if you're going to buy one, I only picked one of the cheaper ones from youtube to show.
It's actually already from 2019, but I picked it for the cheap price and to show what it can do.