Integrating ElIoT CLASSIC into HA for house consumption monitoring

I’ve ElIoT CLASSIC LoRaWAN on my electrometer. It reads data from the electrometer’s optical port and sends it to the cloud via the LoRaWAN network. Data are available in a web application. But API access is also available. I can get data via MQTT or REST API output is JSON in both ways:

"high_rate_kwh": 1234, // spotreba ve vysokem tarifu
"low_rate_kwh": 1234, // spotreba v nizkem tarifu
"fcnt": 12, // citac zprav
"timestamp": 44558, // cas prijeti zpravy jako unix timestamp
"crc": 256, // crc serioveho cisla elektromeru a hlavicky zpravy elektromeru
"battery_state": 254, // stav baterie: 255 - neznamy nebo zarizeni pripojene do zasuvky, 254 = 100%
"rssi": -95, // rssi nejlepsi prijimaci gatewaye
"snr": -16, // snr nejlepsi prijimaci gatewaye
"network": "LoRaWan", // sit, pres kterou jsou data prijata. Bud LoRaWan nebo NB Vodafone (deprecated)
"networkId": 1, // Network provider ID the data came identifikator site, ze které prisla data
"lat": "50.7117478", // latitude nejlepsi prijimaci gatewaye
"lon": "15.2336692", // longitude nejlepsi prijimaci gatewaye
"values": [{"metric": 1, "sub_metric": 1, "value": 1}],
// krome vysokeho a nizkeho tarifu jsou zde uvedeny dalsi prenasene hodnoty
// "metric": metrika: vysoky tarif = 1, nizky tarif = 2, 11 = uzivatelsky definovana hodnota, kterou dale rozlisuje "sub_metric"
// "value": hodnota

I’m looking for a way how to implement this into Home Assistant. I didn’t find any finished integration, and the company that developed this device doesn’t know about any integration. I’m an experienced Perl programmer. I’ve also some Python experience. But I’ve basic knowledge about HA, I’m running it just for a month.

Please, can someone point me to the right place in the documentation? Or to a similar device, I can use as inspiration for work I need to do? Thank you!