I'm pretty sure you can network Macs together via the latest Thunderbolt standards and get pretty decent performance overall. Sure, it will be a bottleneck to some extent but it's still useful for many purposes.
Yes you can do that and shard a very large model across the devices but it's way too slow so you will get no performance gains beyond being able to run a much larger model at all.
Yes you can do that and shard a very large model across the devices but it's way too slow so you will get no performance gains beyond being able to run a much larger model at all.