Read what exception 1 to 408.36 says carefully. The typical split bus you used to see in small "loadcenters" where there is space for 6 mains and one or more of them supply second bus structure in same panel - is what is no longer acceptable, and possibly a few other configurations once available.
Here is a link to something fairly new that some may possibly call a "split bus panel", but it does comply with the requirements in 408.36 exception 1. Good picture on page 7 of one bus section that is separate from the main bus section, but both sections are supplied by same main - which they did a poor job of showing in that photo - there is no supply (main breaker or main lug) in that photo, but I'd say it would need to be supplied with a "main" breaker in one of the I-Line positions, you could find a main lug adapter to plug on I-Line bus structure, but then you would have all remaining I-Line spaces plus all the QO/NF spaces in the left section as "mains" and a clear violation of six disconnect rule if this is service equipment or the main panel of a feeder supplied building.
Getting back to OP though what is the purpose for different panels? How does different panels for lights, receptacles, or other loads make them more energy efficient?
I can understand different sources having some benefits, but if that is what you are after the panel I posted a link to or even the old typical split bus panel are not working so well with multiple sources feeding them anyway.
Also remember that a panelboard and a cabinet are not the same thing - I guess you could have multiple "panelboards" in the same cabinet - which really IMO is pretty much is what we have in the link I provided
