Long term statistic for not listed device_class (e.g. distance with meter measurement)

Currently (version 2021.8.6), the longterm statistic can be used with sensorEntity that respect the following :

All sensors with a unit of measurement of % are automatically tracked. Other entities opt-in based on their device_class

There is no device_class that match distance.
Please can we add a device_class for meter ?

(The purpose is to follow tide wave for a long period)

More generally, can we have a generic device_class

Thanks in advance

HA is complaining that my ultrasonic sensor measuring the salt level in my brine tank has no device_class yet there appears to be no device_class for distance as OP pointed out. Can something be added?

Device class are available here : Sensor Entity | Home Assistant Developer Docs (home-assistant.io)
Perhaps, can you do a pull request on the subject.
Salt Level seems to be a concentration like nitrogen_monoxide.