Solar with grid connectivity, but no networking?

Spouse and I are trying to get bids from local solar installers and we'd appreciate some crowdsourced knowledge from Tilderinos. Questions first, then some context...

• In the current market, is "no, your equipment can't talk to the Internet" actually an unreasonable demand?
• Is there a term or phrase we should be using to look for, or guide installers towards, solar setups that fully function without Internet access?
• Are there any equipment types -- microinverters, for example -- that definitely will not work due to architecture?
• Are there battery controllers, or central inverters, that are known to play nicely (read: can be expanded later) with batteries from other manufacturers?

For each installer, we start the conversation with "it's essential that the system work entirely offline, without Internet." We're flexible on nearly everything else: system size (probably ~15kW), number of panels, battery, etc. Our first concern is making sure that a 25-year investment is not dependent on some company's cloud servers; secondly, that we're not inverting our dependency graph by making our electric power reliant on the whims of our ISP. There's also the privacy angle. But we're not looking for a totally off-the-grid setup, just trying not to lock ourselves into a bad purchase.

So far, one third of the installers (3/9) have immediately told us we're unreasonable and to just go away. Two others said "sure!" and ghosted us afterwards. One was a little more forthcoming, saying that the equipment requires periodic connections to the manufacturer for monitoring and they couldn't provide a warranty without it. The last two provided bids, but it's difficult to tell if they're telling the truth given the conflicting info we've seen.