No maker can support MKV because.. Are you ready for this? MKV files are containers. That is, you can't know what the video is encoded inside that MKV containers.

So my answer is no. Not all files should play. Often this is the first encounter for some with encoding and all about this is more than fits in this reply box here.

As to what to buy, the usual is your PC. It's very capable of rendering such things.