[Help] HEATING REGULATION : Items MQTT json listing selection

Hello World,

New on openhab and already a fan !
My old regulation experience some trouble and limitation.
Due the expensive price of a new, I’m working on a python project to control my Central Heating Boiler.
I’m going to share it when the project goes full runing.
To help comprehensing of this subject, I name my Central Heating Boiler : REGULATION
It’s a Raspberry with Relay, Heat Sensors, Sqlite for settings all part controlled by python.
To remotely control some setting and running mode, it I use MQTT.
REGULATION can already send information to OPENHAB about relays state, sensors information with MQTT.
REGULATION sends a list in json of running mode to mosquitto, I want to use this list in a selection function in openhab, how can I define the items files and use the list to change the running mode with basic ui

here is my actual REGULATION.Items

Thanks in advance for your Help

Switch REGULATION_Reachable “REGULATION: reachable” (gReachable)
{ mqtt="<[broker:tele/REGULATION/LWT:state:MAP(reachable.map)]" }
Number REGULATION_Temperature “REGULATION: Température [%.1f °C]” (GF_Basement, gSensorTemperature)
{ mqtt="<[broker:tele/REGULATION/SENSOR:state:JSONPATH(temperature)]" }
Switch REGULATION_Relay1 “REGULATION: Relais 1” (GF_Basement, gSwitch)
{ mqtt=">[broker:cmnd/REGULATION/RELAY1:command::default],
<[broker:stat/REGULATION/RELAY1:state:default]" }
Switch REGULATION_Relay2 “REGULATION: Relais 2” (GF_Basement, gSwitch)
{ mqtt=">[broker:cmnd/REGULATION/RELAY2:command:
<[broker:stat/REGULATION/RELAY2:state:default]" }
Switch REGULATION_Relay3 “REGULATION: Relais 3” (GF_Basement, gSwitch)
{ mqtt=">[broker:cmnd/REGULATION/RELAY3:command::default],
<[broker:stat/REGULATION/RELAY3:state:default]" }
Switch REGULATION_Relay4 “REGULATION: Relais 4” (GF_Basement, gSwitch)
{ mqtt=">[broker:cmnd/REGULATION/RELAY4:command:
<[broker:stat/REGULATION/RELAY4:state:default]" }

I’ve try this but I’ve an error

Selection REGULATION_Mode “REGULATION Mode: [%s]” (GF_Basement, gSelection)

Selection for sitemaps only. It is not an item that can be used in rules.
I don’t think you can do what you intend to do I am afraid.