Software IoT opensource (consulting)

NO PLACEHOLDERS. Do not insert a placeholder: please read the project details carefully because here are all the details you need to make an accurate estimation.

I need to identify, install, and configure open-source software that allows me to remotely manage IoT devices without using an MQTT network. Currently, I intend to manage control units that oversee already installed environmental sensors performing:
• temperature monitoring
• humidity detection
• air quality measurement

The connectivity currently available on the devices is based on FTP; the control units are equipped with a telephone SIM.

The goal is to have a dashboard that allows for viewing device status, monitoring data flow from devices, performing tasks on devices (such as firmware updates), etc.

Environment: Windows Server 2019.

I am therefore seeking consultancy from an expert systems administrator who can:
1. recommend the open-source software best suited to the described requirements (as an alternative to Tailscale, which is being phased out);
2. define the minimum required architecture (servers, communication protocols, security, automation);
3. prepare a step-by-step guide for installation and initial configuration;
4. present a brief operations and maintenance plan.

We found some products online, such as OpenRemote (https://github.com/openremote/openremote).

I accept documentation in Italian or English.
Solutions must be manageable solely on Windows systems, without Docker, VMs, or WSL.

We have a local/private AI in place; we are happy to evaluate potential complementary solutions that leverage this AI for monitoring and security purposes.