Conversion of WMBUS modules of Apator into pulse counters for Home Assistant

On well-known portals, you can find Apator WMBUS modules for around 20PLN, which were used to read water meters. I would like to use them in a home automation system with Home Assistant to report the status of the electricity and gas meter. The energy meter has an OC output and the gas meter has a reed switch. The solution on WMBUS seems rather reliable (battery power supply and transmission of absolute status).

I disassembled such an Apator overlay and as you can see in the photo, we have a diode transmitting infrared pulses and three photodiodes. To change the status of the counter, you have to short-circuit the three diodes one by one - this imitates the rotation of the dial on the water counter. So now I need help in making such a say interface pulse input -> shorting the three photodiodes. What comes to my mind is a sleeping atmega 8, which after waking up would short-circuit the photodiodes one by one with some delay (but I don't know if this solution would not drain the battery). Well, unless someone has a simpler idea? I'd love to get feedback on how to do this most simply. Thanks for the suggestions

Can you complete the entry and include an even clearer photo of the microcontroller itself and the circuit for the 868 MHz radio, or provide captions of these components?

Does the Home Assistant already have some kind of RF signal reception system (e.g. on RTL-SDR) in operation at your home, e.g. for reading water meters?
Do not the electricity and gas meters transmit an RF signal that can be decoded by wmbusmeters (e.g. Tauron Amiplus, apator, echelon)?
Does the possible choice of atmega 8 result from the fact that you already have such a procec in the drawer?
In the presented concept, it would probably be necessary to start by measuring how often the diode transmitting infrared pulses is switched on and for how long. It would be best to measure this with a logic state analyzer or, in the absence of one, try to measure it with an IR frame analyzer (built temporarily for testing e.g. on an atmega 8 and an IR receiver). Once the switching frequency of the IR transmitting diode of the WMBUS Apator module from the water meter is known, it will be possible to synchronize the own µc circuit with this, when it should switch on (simulate) the three photodiodes. It seems that such information is needed because with the transmission of its own information to the three photodiodes probably should be hit at a time when WMBUS Apator is awake.
Probably in the picture by the proc is a watch quartz.

This is how Amiplus already reads (wmus) hence the idea was to use my RTL-SDR to read the other utilities. The water meter has a LoRy overlay (grrr - can't read it off the air) - I read it using 'AI on the edge', but I plan to fit my water sub-meter. Unfortunately the gas meter only has a pulse output (regular reed switch). Very good idea with this sync with the overlay transmitter diode - I played around a bit. I added my IR LEDs and started illuminating the overlay photodetectors. It manages to change the state reported by the overlay. It works quite well.

I discovered, however, that the overlay doesn't really "like" it when I change the state too quickly. E.g. my electricity meter (I have an extra one with an OC output) transmits pulses every 0.5Wh. It happens that the pulse is every 1s - that's too fast for this overlay (probably the water meter dial doesn't rotate that fast). In addition, at night the overlay very rarely sends out frames.

I am finally testing solutions for the gas and energy meter (the one with the OC) based on ESPHome on the Wemos D1 Mini Pro v2. This is the version with the LI-Po battery charger. It has not lost a single pulse in the last 48h. There is a service in HA to set the initial value Anyway, thanks for the help and ideas .