I see now why you need an all in one device.
But it does limit your choices a lot.
It’s not something that I’ve really looked into, but it seems now that the only devices that support all UK catch-up apps are Amazon,Apple TV and smart TVS.
I don’t think the Chromecast supports Channel 4.
I find it a bit ludicrous that there isn’t more devices that support free to air UK catch-up channels.
It’s probably all down to the UK TV licensing laws.
Also, Amazon and Apple are in the top five richest companies in the world so that might have a bearing on it as well.