They don't do any of the Dolby decoding and multi-channel mixing. Their closest product is the miniDSP Flex HT which is really about applying EQ to a bunch of channels (only 8, aka 7.1 or 5.2.1) after they've been decoded by an upstream receiver. It's pretty niche.

I use the miniDSP 2x4 in my office right now to split the LFE and filter out the room modes.

It's amazing the difference you can make with a basic DSP engine and a tape measure.

MiniDSP doesn't do any bitstream decoding.