- The adafruit guides have individual links. We can consolidate those to reassemble the 2.x parts list again. I am currently focused on 3.0 release, and would prefer to do such work as part of 3.0 release (and hopefully this time we'll have more stable links, with static part details). I like the idea of source controlling the BOM. The website itself is under github.com/reef-pi/website, and a BOM is present there as well (not with as much details as I would love to). So we can start with improving from there.
- Would love to get any and all type of contribution, code, design improvements, docs, translations, build threads.. anything that help the project in any way.. we appreciate all of it

- Can you expand on the broken down bits aspect. Currently the design aims for extensibility and modularity. wich is you can build a single unit powered by pi zero and only with one module or a combination of many modules. In the code its pretty well segragated (reef-pi/controller/modules), there are horizontal libraries (drivers, telemetry, storage etc) that are seperate repos or standalone packages. The nano/pico/premium distinction is in the electronics/enclosure land ... not so much on the software side from design. It does bring in new performance challenges, but thats a different aspect. Most cases we know the safe limits, or we get to see when we are crossing it
- Bunch of the sensors you mention are already supported, some other will work without much changes (e.g. ezo based ec and orp probes) but not cleanly (modeled as ph), in 3.0 we have done some foundation work on driver side (Hardware Abstraction Layer) that will make the ground up support for new probes very easy. tplink smart plugs (kasa) are based on this. I hope to write many more as part of 4.0. Humidity is one of the main one.
- Selling ? Not really in that way. I dont think I can legally do that, neither I find it makes sense financially. And I am definitely pretty lazy when it comes to shipping etc.. But if you are in bay area, and willing to pick up manually, then I'm up for giving it away for a beer

. I'll have to get rid of them some way, as I want to iterate and print newer models, I am learning a lot on that front recently.
Thanks for giving reef-pi a shot,