4 USD × 500 is cheap next to radio certification. Take an nRF52832 module that carries its own FCC ID and CE paperwork (Raytac MDBT42Q is the one our lab uses), follow its layout rules for the antenna keep-out, and you only need the cheaper unintentional emissions testing for the whole product. Keep your firmware as is, the chip is the same.

For Hermetry: the tags themselves never log in. You put a BLE gateway on each floor (a Pi or any box with BLE and network) that listens to the adverts and reports each tag as a child device over the gateway API:

v1/gw/telemetry
{"tag-C4A1F0": {"values": {"temp_c": 4.2, "batt_mv": 2950}},
 "tag-C4A1F7": {"values": {"temp_c": 6.8, "batt_mv": 2910}}}

Hermetry creates each child the first time it sees the name, puts it in the gateway profile’s „Profile of new children“, and children never have credentials of their own. That answers Emily: one token per gateway, three or so per building, nothing per tag. A gateway takes up to 500 children by default, and each child counts toward the plan’s device limit.

If two gateways on neighbouring floors hear the same tag, decide in the gateways which one reports it, otherwise you get it twice under two names. Details: Devices behind a gateway.

Rachel’s guess is the likely one. Same module, different carrier board. Both have an ESP-12E with the ESP8266 on it, so your sketch and pins are the same.

The narrow one is the „v2“ style (Amica design): CP2102 USB-serial chip, fits a standard breadboard with a row free on each side.

The wide one is the „v3“ style (LoLin): CH340G chip, wider so it covers all the holes of a normal breadboard, and the VU pin, which is the 5 V from USB. Handy if your photo-eye’s interface needs 5 V.

Windows 10/11 usually has the CP2102 driver, not always the CH340 one. Install the CH340 driver from the chip maker (WCH), unplug and replug, and it’ll appear as a COM port. If it still shows nothing, try a cable you know carries data, a lot of short USB cables are charge-only.

For the six counters: pick one and stick with it so wiring and enclosures are the same. I’d take the narrow v2 if you prototype on breadboards and the v3 if you want the VU pin. And count the pulses with an interrupt, then send one number per minute, not one message per pulse.