Here is the first sub-thread of the main Hestia32 thread.
This is one is about deciding which ESP32 board we will choose.
Candidates:
They are both pretty similar with differences that will not matter in Hestia32. We think we will choose depending on the most “popular” layout (30, 36 and 38 pin count). They come in USB-C versions which we like 
I’ve used various pin counts of ESP32 boards and it seems that the extra pins you get over 30 aren’t terribly useable, they’re tied to different things on the board that make them behave strangely if used… Supposedly anyway, I haven’t actually attempted to use those pins. So my 2 cents would be to just stick to the 30 pin boards. Beyond that I have no preference on brands.
It looks like the availability of these two are not very good…
Given the problems that we’ve run into with getting the Pi Zero boards over the past few years, I’m pretty interested in lobbying for something that is going to be available, in-stock, and normally stocked, ideally with the option of multiple retailers (Mouser, AdaFruit, etc.).
In contrast the ESP32-S2-SOLO-U-N4 is in stock, normally stocked, don’t require buying in bulk and they only cost $2.15 USD/each (+ shipping)
Components like this are great for mass production but not so much fun for the DIYer as they lack the pins and easy programmability (missing the USB and all components in between). They are also practically impossible for the average DIYer to replace if burned during extreme hacking
…but I see your point.
I got my test samples off my beloved Asian market not thinking availability will be an issue for US/EU 
Fair points. We could solder this to a board with male headers to make it easy to replace, but if we also include a USB to serial adapter, then I agree that it makes more sense to just pick a development board which has all of this built in. It’s a trade off between cost and making it easier for people who want to solder together their own thermostat but don’t want to have a programmer separate from the ESP chip.
As long as they’re going to be available for long into the future, it doesn’t make much difference to me which one is chosen.
The cheaper we can make it, the more people will likely be willing to give it a try, but I think the cost is going to be dominated by the screen and AC/DC converter for this model. A $5 ESP isn’t going to make much difference over the $2.15 version.
My vote would also be for a dev kit for the reasons mentioned above. You also mentioned a screen being a major cost for this… Personally with the HestiaPi system I put together, I never bothered with a screen. I just use it on the app when needed or let the automation handle the changing of setpoints on a day to day basis. I don’t think I’ve ever had a problem with it not responding on the app. I would also venture a guess that most people are going to probably have an Openhab Server running or some other home automation service that they would integrate their Hestia32 system into for control. I have found it’s so much nicer to just do it from my phone, then I can change it from anywhere in the house. But maybe the majority of people wouldn’t think that way.
I strongly agree with what @rlkoshak said in another thread about the Hestia32 being a functional thermostat without any backend like OpenHAB. If there’s a problem with your server, it shouldn’t mean that your house doesn’t get heated/cooled properly or that you can’t control the temperature. This adds complexity, but I think it’s important since we can’t control how well the back end is configured/maintained nor whether the wifi sometimes goes down, etc.
The closest I could imagine to a no-screen model would be something that would hold steady in the event of a disconnect (which means using a local temperature sensor, which is possibly a change from a remote sensor) and start up an access point with a UI that allows the user to control set points.
I feel like the default configuration should be with a screen so it’s super easy for everyone to use. If someone wants to save some money and get one without a screen, we should make it clear how much functionality and support they should expect (as remotely troubleshooting issues for people would be much harder without a screen).
Although I rarely use the screen myself I can see many use cases where a screen is important. It is so much easier to design it with a screen, UI, etc and whoever prefers if headless customise the case and not include the screen
Remember, as with many other discussions about features here in this forum, we usually go with the solution that accommodates the most people.
I need to start putting things together at some point and finalize the hardware, feature set for the MVP and make our first steps on the PCB and code repo…
Fair enough! I just wanted to make sure it was discussed at least!