Much like your setup their are sensors fitted to various infrastructure connected to PLC's connected to licensed uhf radio modems back to a base station (with a few hops through repeaters or microwave backhaul) into a PC running some kind of IO server which handles all the polling and collects the data into a database and SCADA software (Aveva).

Its a weird mashup of hardware and protocols (dnp3, modbus, serial) plus some data coming in through IoT devices over http and all sorts of bits.

All i built was a python script that runs the query (we are talking 200 bits of data) every minite and dumps it into a JSON file. Then there is a caddy server which serves the json, SVG (1.5mb uncompressed) and a vanilla html/javascript (300 ish lines of code, AI helped get started) page that displays it.

Its not open to public, nor is it a replacement for SCADA (SCADA has many many more objects plus the ability to control and send out alarms). There are many more people wanting 'view only' access than the city has pricey SCADA licenses for, so if fills this gap for free. Sorry i can't share more, i moved on from that job.