kamikatze

thats an opentx "bug", also present on any other otx radio. ajust got a sub setting, which allows you to specify the behavior. standard is "set", any other setting can...

as the quickest solution, you can get the matek boards which provide voltage, current, baro (only baro altitude, but nor rise/sink rate for vario), and PWM outputs

sounds like you also need a fuel sensor. maybe the [openXsensor](https://github.com/mstrens/oXs_on_RP2040) project is what you are looking for. Not sure if the CRSF implementation is already done or under development...