I have some curious design questions, which may sound critical, but my intend is absolutely not to be rude or anything 
Why the need for the separate emonVs? Putting all those electronics in the same housing would make the device simpler and possible cheaper? (I’m currently looking at the https://community.openenergymonitor.org/t/emporia-vue-2-alternate-firmware PCB design and think they solved some issues quite elegantly; I do not own one 
). I know for a start-up getting all that compliance and EMC done is a big PITA, but since you are already designing your own PSU, what’s the reason now?
Why the galvanic isolation on the voltage input? The Emporia doesn’t do it; and they are certified to sell world-wide. I can get it in mainland EU, and NA. Are transformers that more accurate then a few big resistors? I think in the end, you still end up with a scaled voltage?
0.333V CT’s seem to be somewhat common. Emporia uses them, I’ve seen them @ $work in our product. But I can’t wrap my head around the sensitivty/accuracy here. 0.333V CT’s would be 666mV across the range, right? But that’s not RMS, so we’ll add about half (napkin style) to get to 999mV or 1V for the CT output. If we VREF is 3v3 that’s a lot of lost resolution? We want to offset the CT’s to make sure they are always positive; e.g. VREF/2. So we would have signals from 1V15 - 2V15.
Looking at Getting the most out of the SAM D21's ADC - Stargirl (Thea) Flowers we actually see however, the the ADC is not so amazing generally. While this speaks of the ATsamd21, I bet that most ADC’s behave more or less the same. What’s interesting to note here, is that the ADC behaves more poorly in the lower half then in the upper half. The emporia seems to account for that by using 1v8 as the offset voltage, bringing that voltage swing to 1v3 - 2v3. Though in reality it’s probably ore like 1v5 - 2v1 looking at https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcAmWDLMgZgBxmcgCxg4CcS6IShWVApgLRhgBQATiKQGwhbKc9uUEJnjsBEoWC6RhyAOxwWAYwnTZQgoTnRR8fQeSMcUaFkhciOQpfldC3BHdNxWAJQlbP8-rNmFZMGgcX2EYBBYAeTUZcFJ+dXAoFgA3Xn4vPglAkFiYLAKw0wiAd3TJQR5IFjLNInKvaoBzCSyhP2SAexBte2F8ZFJZVDAEQekx7h8hhRdXOSpeFiA for example. Sadly for the atsamd21 at least, the dynamic range of the ADC doesn’t seem to be specified …
Still, I wonder would it not be worth-while to use a CT at 666mV. I’ve been eyeing the https://talema.com/products/az-series-flying-lead-current-transformer/ for example, and the 25 amp model would be good for 16 amps (24 amps RMS) would give 1.5 p2p so 3V0. Of course in this case we’d be in the ‘dirty region’ of the ADC, so we’d need all the tricks on that earlier page, so maybe the talema CT is just a little too much maybe?
Another option would be to use an input gain of 2, but that would actually introduce noise too … or use smaller reference voltages I suppose …
Finally, I really dislike clamp CT’s personally. They take up a lot of space, and bring lots of accuracy risks due poor mating of the clamp. Will solid ring coils ever be an option? They tend to be much smaller … For example I really like the MLG-WST-0200 30 amp https://www.measurlogic.com/product/mlg-wst-solid-core-ct-333mv-output/ on paper, but not buyable for mere mortals (afaik an OEM only product) (hence why I was looking at the talema ones, as digikey stocks those …)