thank you. one thing I should mention is that my idea would require "proof of work/capacity" for the main chain.

This is a sidechain scaling idea. I truly feel like it can rival tron's confirmation times, but it's a side chain. I don't think that's a problem.
The only argument i've seen against proof of capacity is its collusion weakness with technologies like sharding.
I've read a bit into sharding, and it seems to have some arbitrary/inorganic configurations. Primarily the 2 3rds vote to validate transactions on a shard.