How will you compete with Goodman/Daikin and needing lineset runs with usually high voltage work and panel upgrades that sometimes come with converting to a heat pump.
If you don't use 24V AC controls i don't think it would take off with any installers and you seriously limit and then hinder yourself needing way more customer support.
What refrigerants are you considering as there is more environmental stuff coming out killing 410A.
You will be competing against installers that can offer 10 year warranties (Bosch, Mitsubishi) without any of the backing of a large company saying parts will still be available and that is a big worry with start ups, at least when nest got bought you can still run systems without the cloud or could swap to any 24V controls system.
I used to be an installer but am out of the trades now and I think you'd kind of off the mark with your shortcomings to the current experience, the biggest issue you're gonna find is duct leakage and contractors skipping out on the testing and then the old vac n run and the new construction builders literally will want whatever is cheapest and gets them through the build fastest (80% gas single stage with a empty coil box is hella common)
I hope you have seen the variety of retro installs that will need to be done as there are still lots of oil burners out there.
Honestly i've almost talked myself into the idea that I should be working on this project. LMAO.
Please tell me you aren't going to rely on internet and at least use local RTD sensors at least.