We have created a variant of psvanstrom’s esphome-p1reader, adapted for the Currently One hardware.
It can be found at the fork https://github.com/andreanielsen83/esphome-p1reader.
If you prefer, you can download the compiled binary from here, and upload it to your Currently One via the web interface.
When installed, you need to provision your WiFi credentials via its Captive Hotspot. WiFi SSID is esp-p1reader, and URL is http://esp-p1reader.local/
When you want to go back to Currently One firmware, upload the latest firmware e.g. Firmware 2.5.8 (state_class measurement)