within the driver code, use names that match whatever the hardware uses. then you can map those onto the weewx observation types when you generate a LOOP or ARCHIVE dict. for example, the hardware documentation might use 'inside_temperature', but the weewx equivalent is 'inTemp'.
the weewx observation types are defined by the database schema. 'wview_extended' is the default schema, but weewx also ships with the legacy 'wview' and 'wview_small' schemas.
you can see what other drivers have done by browsing the 'Station data' section for each driver in the hardware guide:
for power/solar/battery monitoring, or hardware that emits observations that are not easily mapped to the weather-based schemas, it is typical to ship a bespoke schema with the driver.