I’m curious what you ended up doing? I see the Emporia Vue 3 is $200 per 16 circuits with a 200A main feeder monitor, and they say “If you have more than 16 breakers you want to monitor (in one panel or multiple), just add another Vue Home Energy Monitor”. So that’d be $400 for 32 circuits or $600 for 48 circuits. On the negative side, integration seems less-than-ideal per Emporia Vue 3 as it’s a proprietary cloud API. Likely fine, but less-than-ideal.
To measure a 200A feeder with Shelly products, I think you’d have to use their CT 400A current clamp with Shelly Pro 3EM-400 for $250. That’s intended for 3-phase, but I suppose there’s no reason it couldn’t measure split-phase? What I don’t know is whether their apps and reporting would work properly by default, especially due to the phase angle difference.
As for measuring the circuits with Shelly products, I don’t think their products are a good fit for typical US panelboards. I suppose you could skip using a panelboard. Many US industrial facilities use 120V and 480V DIN-rail mount circuit breakers in UL 508A custom electrical panels. But getting 30 single-phase circuits in an industrial control panel versus an equivalent residential panelboard is at least double the price in my experience. Also I have no idea whether the products for industrial control panels meet the code requirements for residential applications. Sure it would definitely work, but your local electrical inspector would have to sign off on it too.