Yes, understood. If you had said iPhone, I would have offered a suggestion that would not have an effect on your phone battery. Since you said Android, I would also suggest ESP32 is likely your best bet.
Here’s a tutorial that explains how you can use an RFID tag with Home Assistant and you can use Home Assistant Device Bridge to integrate it back to Hubitat.
There’s a thread here and a particular post that might help you get ESPHome running directly on Hubitat.
