Nexia and Allergion

While in Twitter, I looked at “Who to follow” and I saw Nexia. Before I follow them, I did a research and I saw the website:

Is Nexia open-source or proprietary? Judging from their website, I think Nexia is similar to Control4 and Crestron being that they have products that are proprietary and locks me in to a vendor.

Is this true? I don’t have time to do a lot of exploring, so I thought I might ask before I follow them and find out their solutions are proprietary.

Next up is Allergion and Allergion (UK) in “Who to follow” list. Allergion provides solutions for security that are proprietary, am I right?

I make purchasing decisions when it comes to having local API, which is very important to me when it comes to integration with Home Assistant. I don’t want to buy home automation devices that require me to create a cloud account.