An analog fallback is a good idea, to be sure your house doesn't freeze when you're away.

> EDIT: Digging around a little more it seems that Mitsubishi H2i minisplit systems don't speak zwave or zigbee, neither does Haier Arctic

There are no mini-splits in the US that speak anything remotely standard. If you want to go with ducted systems, TRANE and others have smart AC units that use "communicating thermostats". The protocol is based on Envirocom system and it's pretty basic.

Good news is that you can still control them by shorting the wires with a traditional thermostat, so you still can have an analog backup in case the regular digital thermostat fails.