Is Apple TV for me?

I have an aging 2009 Mac Mini as our primary streaming device into a good but older LG TV. The Mini is showing signs of being ready to give up.

Being old farts, we primarily watch Amazon, Acorn TV, and Brit Box and want to keep our monthly subscriptions to a minimum.

Is Apple TV a logical replacement for the Mini?

Do we need to have an Apple TV subscription?

How's the WiFi reception? We're in a very old farmhouse where the plaster-and-lath walls tend to get in the way of WiFi (the Mini does well when on its side).