Here’s some possibilities –
- CABLE (Connect ANT+ to BLE) - North Pole Engineering, Inc. Store (npe-inc.com)
- New or used small form factor Android phone to run EBC.
Example: Cubot King Kong Mini 2 - General - Xert Community Forum (xertonline.com) - Garmin quarter-turn adapter for back of phone (or back of phone case)
Example: Xert EBC - Garmin out front mount; several brands/copies available
Example: https://www.amazon.com/KOM-Cycling-Garmin-Carbon-Designed/dp/B01MSWB5FW/ - Stages or 4iiii left crank meter
Another phone option is a used Android phone (smallest you can find with decent battery life) plus a stem mount like this one:
Amazon.com: Bone Bike Tie Pro 4 Bike Phone Holder for Stem Mounting 4.7” - 7.2” Screen Smartphones, Face ID Compatible, Ultra Light Weight Bicycle Phone Mount, Designed for Road, Race & Touring- Black: Automotive
No SIM card needed. Use phone as your bike computer and connect by Wi-Fi to XO as required. Disable Wi-Fi hunting on outdoor rides to save battery.
Also note many used Samsung models will have ANT+ chip onboard so you could nix the CABLE bridge and the phone will connect to all your sensors. The crank meter will be dual protocol.
So least expensive combo would be used Samsung phone with ANT+ with the looping stem mount above plus a left crank meter. 