Hi all, this is my first post.
I am a self-taught IT enthusiast, and I own a boutique hotel in Santorini, with 14 jacuzzis in a mixed environment. Some are controlled via Bacnet BMS, some with basic Philips-Dynalite (KNX like) switching, meaning pump and heat request without temp monitoring, and some only locally. Energy bills skyrocketed last year and guests are complaining if the jacuzzis are not warm enough, if they are too hot producing a lot of humidity etc, I have decided to take things under control and create an environment where I will have the option to monitor, operate and do energy management, and the guest will be able to access the room's system with just a selection of the operating profile between ECO, moderate or VIP and the option to further adjust the temperature and shut the thing on or off.
So I purchased for each of the 9 systems 1 Shelly 3 pro to control the heater the Pump and the Jet Pump, plus 1 Plus 2pm for lights and water level with the addon and two sensors, one for Temp and one for Heater Outlet to be able to calculate Delta. For the 5 ones on the BMS, I purchased 1 Plus 2pm with the add-on and five Temp sensors for the heater outlets. I installed HA OS on my Proxmox cluster and started playing.
Although with zero coding skills, I borrowed some code from the net and with the help of my new friend and colleague ChatGPT-4 
, I managed to create quite spectacular results on my first sample, but it is obvious I am lacking the deep knowledge. I created some nice cards on HA, controlling everything from there.
This is guest's view pasted-from-clipboard.png and this is operator's view pasted-from-clipboard.png
However, due to the harsh Wi-Fi environment where disconnections are a probability, I believe the safest way to go should be to assign the operation to the Shellys so they always work, and use HA only for control and monitoring. I am a little lost, between HA, MQTT, nodeRed, ShellyforHash or just integration etc, I am not sure on which approach to follow, or in other words, how would an expert do it?
Some more challenges ahead, like connecting to my PMS that supports FIAS protocol to get check in - check out information for energy management automation, and guest name to use as password while logging in through QR code scanning, so access expires upon check out etc.
Any ideas on how to move on the next step? Outside help is of course welcome, so anyone interested, please contact me for communication.
Thanks in advance