If people have a preferred way of integrating their devices, like home assistant, I'd want to make that possible for people to do with Electric Air.

Re the sizing question - this is a part of the site that needs improvement. 12kbtu is 1 ton. The 48kbtu system is a 4ton system, but rated at 5F, if you're in a more temperate climate, two of these will likely have plenty of capacity for you. It's also likely that your current system is oversized.

As someone about to be in the market for something like this, propriety lockout is a complete deal breaker for me.

/2¢

The good news, at least, is that almost anything will work. You don't need full Matter support for Home Assistant folks to be happy. The bare-minimum, local REST api built on a Monday by an intern will do it. Someone will write the Python code to fully integrate it. I get that there would be some security concerns there, but you get my drift.

If worried about security concerns, just provide a common port interface (RJ-45/RJ-11) on the unit with a simple, well-documented, serial-based protocol on RS485/RS232. You can sell an add-on device to bridge that to Ethernet/simple API, and easily replace/recall that inexpensive module if there are issues.

The hackers will do what they want to anyway, and they'll implement cool interfaces/HA plugins/controllers on RPis or ESP32s for free. Someone will get enterprising and package a pre-built/programmed ESP32 unit that makes it plug-and-play for nerdy, but less capable users, and your company can avoid any liability from users using an 'unsupported' add-on.

Also, I'm in the market for a new AC/heater - so have been looking.

Your specs are in kbtu, but at least for cooling I'm used to tons; I have 2x4.5ton units, and I think that's ~120kbtu, so I wouldn't be able to get just two of your biggest units?

That would be 108kbtu, but you are likely oversized. With proper duct configuration including ACCA Manual D calcs and air sealing, you will most likely be more than fine with 96kbtu. Most systems (even in very nice houses) are just sort of thrown in rather than actually calculated, and then they are installed sloppily with a lot of leakage and only roughly resembling the design in at least a few locations. I do these calculations for a living, and would recommend presuming that will be the case until proven otherwise. Obviously get hard numbers before full commitment.